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The “UWlestininster” Series 


WOODS PULP AND Ils UsEs 


WOOD PULP 


AND TES USES 


C. F. CROSS, E. J. BEVAN 


AND 


R. W. SINDALL 


WITH THE COLLABORATION OF 


Vie Ne eb A CON 


NEW YORK 


D. VAN ‘NOSTRAND CO 
TWENTY-FIVE PARK PLACE 


IQI4 


10 JUN 14 bin 


MoOlurg. 


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7 


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Vhemiatry, 3de 


PREFACE 


Tue world has had its Stone age and its Bronze age: later 
its Iron age, and the present is a Cellulose age. 

This is not said ad captandum ; it is a statement which 
will survive critical examination. 

The volume now offered to students and the general public 
is based on studies in the domain of cellulose, -both theo- 
retical and scientific, and practical or industrial. 

It is not a monograph or a text-book of the subject: it 
does not pretend to be systematic or exhaustive. 

Technical literature in these days threatens to develop to 
formidable dimensions; and systematic works on branches 
of technology: necessarily carry a large weight of fact and 
information which is common groundwork. 

We have only given an outline of what appears essentis] 
as a cyclopedic framework. We are not addressing our- 
selves particularly to the specialist, nor to the technical 

student. Rather to the general reader, and our aim is 
therefore to give a general account of the evolution 
of the wood pulp industries, as typical of the age we live 
in, and as a very substantial contribution to its primary 
necessities. 

But if wood pulp has had an interesting past history, its 


280019 


vi PREFACE , 


future is suggestive of many more interesting possibilities 
of which we endeavour to give indications. 

From whatever standpoint in fact the subject is treated, 
if challenges attention. 

The chemist, the manufacturer, the political economist, 
and of course the financier will find that it teems with pro- 
blems the solution of which carries rewards of great moment. | 

In an age when pessimists see little but competitive 
exhaustion of sources of natural wealth, it is satisfactory to 
be able to present a domain still full of unexplored possi- 
bilities. Such is the subject of ‘“‘ wood pulp” or, more 
broadly, “cellulose,” and we trust this imperfect contribution 
will help to sustain and awaken the interest of readers and 
students. 

We have pleasure in acknowledging the valuable assistance 
of Mr. W. N. Bacon B.Sc., F.1.C., in contributing matter 
and revising proofs. 

We are indebted to the Royal Society for the privilege 
of reproducing illustrations from papers of the late W. J. 
Russell (p. 73). ‘lo Messrs. Longmans, for permission to 
reproduce portions of ‘‘ Researches on Cellulose,’ II. 

The illustrations in Chapter I. are chiefly from original 
histological studies of Messrs. Flatters, Muilborne and 
McKecnine (Longsight, Manchester), whose excellent work 
in this field is well known, or sheuld be, to all students of 
Botany. 


CHAP, 


Iit. 


CONTENTS 


THE STRUCTURAL ELEMENTS OF WOOD .. . 


I. CELLULOSE AS A CHEMICAL INDIVIDUAL AND 
TYPICAL COLLOID. Il. THE LIGNONE COM- 
PLEX, LIGNO-CELLULOSE ; SPECIAL CHEMICAL 
NOTE ON AUTOXIDATION, AND RESEARCHES OF 
W. J. RUSSELL . : : . . . 


WOOD PULPS IN RELATION TO SOURCES OF SUPPLY: 
FOREST TREES AND FORESTRY 


THE MANUFACTURE OF MECHANICAL WOOD PULP 
CHEMICAL WOOD PULP 

NEWS AND PRINTINGS 

WOOD PULP BOARDS 

THE UTILISATION OF WOOD WASTE. 

TESTING OF WOOD PULP FOR MOISTURE . 

WOOD PULP AND THE TEXTILE INDUSTRIES 
SPECIMEN PAGES—VARIOUS TYPES OF PAPER . 


BIBLIOGRAPHY . 


INDEX ° . . : . : : ° . 


PAGE 


FIG. 


SN) 


De 


Pi oieOE SIP EUStT RA PIONS 


TRANSVERSE SECTION OF STEM OF TRADESCANTIA 
SHOWING EPIDERMAL TISSUE, PARENCHYMA CON- 
TAINING STARCH, AT THE CENTRE A VASCULAR 
BUNDLE 

TRANSVERSE SECTION OF A YOUNG STEM OF PINUS 
SYLVESTRIS (COMMON PINE). BELOW, PRIMARY 
GROUND TISSUE FOLLOWED BY WOOD IN DEVELOP- 
MENT AND IN SUCCESSION CAMBIUM BAST AND 
CORTEX. IN THE CENTRE IS A MEDULLARY RAY 


. TRANSVERSE SECTION OF AN OLDER STEM OF PINUS 


SYLVESTRIS (COMMON PINE) SHOWING DEVELOP- 
ING BRANCH, A MORE ADVANCED WOOD SYSTEM 
AND EXTERNAL TO THE LATTER THE CAMBIUM 
AND PHLOEM TISSUES . 

LONGITUDINAL SECTION VASCULAR BUNDLE OF ZEA 
MAIS SHOWING SPIRAL, ANNULAR, AND PITTED 
VESSELS. SURROUNDING THE BUNDLE IS THE 
GROUND TISSUE OR PARENCHYMA : : : 

LONGITUDINAL SECTION OF STEM OF GOSSYPIUM S.P. 
(COTTON PLANT) SHOWING FROM LEFT TO RIGHT 
PITH, SPIRAL VESSELS, CAMBIUM, PHLOEM, COR- 
TICAL TISSUE, AND CUTICLE A 

TRANSVERSE SECTION OF STEM OF ZEA MAIS (INDIAN 
CORN). VASCULAR BUNDLES SURROUNDED BY 
PRIMARY GROUND TISSUE. EACH BUNDLE CONTAINS 
LARGE PITTED AND ANNULAR VESSELS WITH 
PHLOEM AND SCLERENCHYMA : L A 


PAGE 


~l 


Y 


10 


me LIST OF ILLUSTRATIONS 


FIG. 

5B. JUTE—SECTION OF BAST REGION SHOWING WEDGE- 
SHAPED BUNDLES EXTENDING FROM CAMBIUM TO 
CORTEX : ‘ : ! : : : 4 

5C. JUTE (MAG. 300)—SECTION OF BAST REGION SHOWING 
STRUCTURE OF BUNDLES AND THICKENING OF 
ULTIMATE FIBRES 

5D. FLAX—SECTION OF STEM OF LINUM SHOWING GROUPS 
OF BAST FIBRES LYING BETWEEN WOOD AND 
CORTEX ; 

6. TRANSVERSE SECTION OF STEM OF LYMNANTHEMUM 
(AQUATIC PLANT). CENTRAL AXIS WITH XYLEM 
AND PHLOEM ELEMENTS. GROUND TISSUE SHOW- 
ING LARGE AIR CELLS PRODUCING BUOYANCY, AND 
STAR-SHAPED IDIOBLASTS | 

7. TRANSVERSE LONGITUDINAL SECTION OF STEM OF 
TILIA EUROPQ@A (LIME TREE), SHOWING BAST 
FIBRES AND GROUND TISSUE 

8. TANGENTIAL LONGITUDINAL SECTION THROUGH THE 
WOOD ELEMENTS OF TILIA EUROP@A (LIME TREE). 
FROM LEFT TO RIGHT A MEDULLARY RAY IS SEEN 
IN THE ROW OF LITTLE CELLS, FOLLOWED BY 
TYPICAL WOOD FIBRES, SPIRAL AND PITTED VES- 
SELS, AND CONNECTIVE TISSUE . ; ; : 

9, LONGITUDINAL RADIAL SECTION OF PINUS SYLVESTRIS 
TIMBER SHOWING WELL-DEVELOPED BORDERED 
PITS UPON THE WALLS OF THE TRACIIEIDS. AT 
RIGHT ANGLES TO THE TRACHEIDS IS A MEDUL- 
LARY. avo. ; 5 

10. TANGENTIAL LONGITUDINAL SECTION OF OLD WOOD 
OF PINUS SHOWING TRACHEIDS AND MEDULLARY 
RAYS; THE LATTER CONSIST OF TWO OR MORE 
ROWS OF CELLS ARRANGED LONGITUDINALLY 


PAGE 


if: 


14 


16 


17 


FIG, 
11A. 


Lis. 


os RS 


LIST OF ILLUSTRATIONS 


TRANSVERSE SECTION OF STEM OF GOSSYPIUM (COTTON 
PLANT) SHOWING ONE ANNULAR RING OF XYLEM 
AND PHLOEM ELEMENTS WITH INTERVENING 
CAMBIUM LAYER. : 

TRANSVERSE SECTION OF A THREE-YEAR-OLD STEM OF 
TILIA (LIME TREE). AT CENTRE PITH THEN XYLEM 
(WOOD) IN THREE SEPARATE RINGS. TOWARDS 
THE PERIPHERY THE CAMBIUM RING THEN PHLOEM 
AND CORTICAL TISSUE... é 

DATE PALM. TYPICAL MONOCOTYLEDON PERENNIAL 

PINE. TYPICAL CONIFER. EXOGENOUS GYMNOSPERM. 

OAK. TYPICAL ANGIOSPERM EXOGENOUS PERENNIAL . 

LARCH  . 

OAK . 

SPRUCE 

SCOTCH FIR ; : : ; : 

VIEW OF HORIZONTAL GRINDER (A), WITH SECTION (B) 

CURVE FOR ILLUSTRATING POWER TRIALS 

SHAKING SCREEN 

CENTRIFUGAL SCREEN FOR WOOD PULP 

SECTION OF CENTRIFUGAL SCREEN FOR WOOD PULP 

DIGESTOR FOR MANUFACTURE, OF BROWN PULP. 

TOWER BLEACHING PLANT 

HAAS AND OETTEL ELECTROLYSER 

CHLORINE CAUSTIC SODA CELL (SECTION) . 

THE ‘‘ HOLLANDER” BEATING ENGINE 

ND 238A. DIAGRAMS OF WEDGE SYSTEM 

SPINDLE FOR TWISTING PAPER-STRIPS 

MACHINE FOR ROLLING FLAT STRIPS OF PREPARED 
SHORT FIBRE (SLIVER) ° 


x1 


PAGE 


19 


WOOD PULP AND ITS USES 


CHAPTER I 
THE STRUCTURAL ELEMENTS OF WooD 


THERE are no more interesting studies than those which 
group themselves under the term Applied Sciences. It is 
quite true that science, or rather the sciences, may be 
pursued from a point of view which ignores the services 
which they render to man; but whereas “pure science” 
is an ideal rather of the imaginative world, the natural 
prosecution of the sciences compels the recognition of their 
organic interdependence with human progress. 

Whichever aspect is the more attractive on general 
grounds, it is clear that the subject of this work is pro- 
minently typical of this. interdependence; involves in a 
particular manner the utilitarian bearings of science, and 
our treatment of it must be accordingly utilitarian. 

Wood pulp is a comparatively modern product called into 
existence as a paper maker’s raw material. The woods 
which furnish the product in its various forms have been 
impressed into the service of man from the earliest, in 
fact from prehistoric, times, and have been used for 
their structural qualities in a large number of our most 
important industries. The uses of the woods are so 


W.P. B 


2 WOOD PULP AND ITS USES 


universally familiar that it would be superfluous to 
particularise them. 

We may, however, preface our specialisation to the par- 
ticular employment of certain woods as the basis of wood 
pulp, by calling attention to the physical and mechanical 
properties of a typical range of woods considered as 
structural materials. | 

For the natural history of the woods as products of 
vegetable life and growth we turn, of course, in the first 
instance to the science of Botany. In the scientific treat- 
ment of plant life questions of utility—that is, the part 
which a plant or any of its parts, seed, flower, stem or root, 
may play in the service of man—has no part. Moreover, 
external features are of quite subordinate moment. 

Thus the cereals which furnish, perhaps, the most 
important staple of our food are to the botanist no more 
important than any other of the great family of the grasses. 
It is not without significance to the botanist that these 
particular grasses have come to be selected and specialised 
by cultivation through countless generations, so as to 
ditferentiate them as economic products. But such con- 
siderations are relatively unimportant, as not concerned 
in those elements of identity and characterisation which fix 
the position of an individual plant in the scheme of botanical 
science. 

So also in regard to external features such as size, form, 
and vegetative habit. The sugar cane or bamboo are not 
obviously related to the cereals, but to the botanist the 
relationship is of the closest. The laburnum and the 
trefoil have little in common as regards form and life 
history, but they are blood relations. 


THE STRUCTURAL ELEMENTS OF WOOD 3 


The relationships are fixed by the more fundamental 
features of the reproductive mechanism; both the major 
and minor differentiations constituting the basis of the 
classifications of botanical science are those of the repro- 
ductive system. These differences necessarily are corre- 
lated with those of the plant body, by which the second 
creat function or group of functions is conditioned, 
viz., those of nutrition. As the reproductive mechanism 
becomes more complex, so the structural type is differen- 
tiated towards complexity. Viewing the plant world as an 
evolutionary series, reproduction by seeds is the last 
feature to make its appearance, and is preceded by those 
differentiations of the plant body which issues in what is 
known as a vascular system. 

Thus in the fern the structural features of the higher 
flowering and seed-bearing plants are recognised, and in a 
tree fern the differentiation into vascular tissue, leaves and 
stems, with the lower portion formed into a root system, 
are apparent. But the reproduction of the fern is on a 
much lower plane, and it bears no seeds. The tree fern is 
a kind of pseudo-morph of the true tree or forest tree, which 
is a Spermatophyte or seed-bearing plant. 

Of the four great groups of modern botanical classifica- 
tion the spermatophytes are much the most conspicuous 
and widely distributed. Moreover, they are so interwoven 
with our experience that their study has often ranked as 
co-extensive with botanical science to the exclusion of the 
other great groups. These are the alge, the lichens, and 
the fungi(Thallophytes), the mosses (Bryophytes), and ferns, 
horsetails, and club mosses (Pteridophytes). The modern 
science regards these groups as related in evolutionary 

B 2 


4 WOOD*PULR AND 2 TsaUisiis 


sequence. ‘There are two aspects of this evolution. The 
one involves the theory of descent, the higher from 
the lower order, as an objective fact; on the other the 
development of the highest type can be followed through 
the lower by the study of the dominant or reproductive 
functions, which thus unfolds itself as a homogeneous con- 
ception of the relations of the infinitely diversified forms of 
plant life. 

We are not concerned with these fundamental generalisa- 
tions further than to indicate their connection with our 
subject. 

We shall have to point out that from the point of view 
of “wood pulp” the trees which furnish these industrial 
products are of two sub-groups, and we have explained the 
basis of classification sufficiently to convey their relationship 
to the general reader in the terms employed by the 
botanist :— 


Spermatophytes 
(seed-bearing plants) 
be i er 
Gymnosperms Angiosperms 
(naked or exposed seeds) (enclosed seeds) 
Monocotyledons Dicotyledons 
(Conifer) Bamboo Poplar 
Pine Spruce Sugar Cane. 


We have already indicated that our subject has only an 
incidental connection with these fundamental relations. 
The plant is a structure, an agglomerate of structural 
elements; and its work as a plant is to grow, to build up 
tissue The assimilating organs of the higher flowering 


THE STRUCTURAL ELEMENTS OF WOOD 5) 


plants are the leaves. The leaf is the centre of the funda- 
mental operation of building up “organic”? compounds 


Fig. 1.—Transverse section of stem of Tradescantia 
showing epidermal tissue, parenchyma containing 
starch, at the centre a vascular bundle. 


from the inorganic form of carbon, viz., carbonic anhydride, 


contained in the air, and of which gaseous mixture it is a 
normal constituent. This characteristic function of the 


6 WOOD PULP AND ITS USES 


plant, the photosynthesis of carbon compounds and their 


Fic. 2.—Transverse section of a young stem of Pinus 
Sylvestris (common pine). Below, primary ground 
tissue followed by wood in development and in 
succession cambium bast and cortex. In the centre 
is a medullary ray. 


elaboration to tissue material, we must take for granted ; 
as well as the complementary function of the root system 


THE STRUCTURAL ELEMENTS OF WOOD 


in absorbing water, inorganic mineral compounds, and other 
nutrient material from the soil. 


¢ 4 
ha 


ET Eades 
SSince 

9 ip ko te 

etn, 


f, 
is 


ae Pe, 
ae 


ee 
oe 


ed 


($3 hy 


Fic. 28.—Transverse section of an older stem of Pinus 
Sylvestris (common pine) showing developing 
branch, a more advanced wood system and external 
to the latter the cambium and phloem tissues. 


We are concerned with the plant as a completed struc- 
ture. The study of those functions and processes from which 


WOOD PULP AND ITS USES 


the structure results, and with which it is in its several 


parts associated, constitutes the branch of the science 


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ito Estep ere om 5 EE oe ene N IR 
saoed ere se € rs A pee ae a0 se 
ee ne a = ne - 12s re = i paeciacsie “ OR Sie isis 
rn rt i i ne Aiea = eset = 
sat "5 pen a . : . 
es ees spiysit bee 


annular, 


b) 


iral 


gitudinal section vascular bundle of Zea 
e bundle is the 


3.—Lon 
owin 


Mais sh 


FiG. 


and pitted vessels. 


Pp 


(eS 


th 


Surrounding 
parench 


ground tissue or 


yma. 


. 


1re 


logy; and students who des 


a more comprehensive survey of the subject-matter are 


referred to the special text-books. 


Vs10 


known as vegetable ph 


Ms 


THE STRUCTURAL ELEMENTS OF WOOD 


Taking the plant as a structure, we find it an assemblage 


Ree 


The typical cell is a 


a aw ae 


. asiseiie 
‘ noo a aaa 
ne 
ees OR Me NEE ma AE i eee 


of units generally known as cells. 


ypium 8.P. 


(cotton plant) showing from left to right pith, spiral 


gitudinal section of stem of Goss 
vessels, cambium, phloem, cortical tissue, and cuticle. 


Fia. 4.—Lon 


spherical body of small dimensions—0°1 and 0°5 mm. 


10 WOOD PULP AND ITS USES 


diameter—and consisting of an enveloping wall enclosing 
the cell contents. 


Fic. 5.—Transverse section of stem of Zea Mais (Indian 
corn). Vascular bundles surrounded by primary ground 
tissue. Hach bundle contains large pitted and annular 
vessels with phloem and sclerenchyma. 

Variations and differentiations of the typical form corre- 
spond with infinite diversity of functions and conditions. 
Typical forms of cellular tissue are represented in 


Figs, 1-2, 


THE STRUCTURAL ELEMENTS OF WOOD 11 


More extreme variations lead to the structural forms 
classed as fibres and vessels. 

These are elongated cells, the length being a very large 
multiple of the diameter. In a general way “fibres ” 
may be regarded as the strengthening elements of plant 
structures, and are of relatively simple form. ‘ Vessels” are 


a = 
ZEON wee 


\ 
econ 
SAN 
Ash 
pw 


=a 


Jute. 


Fic. 58.—Section of bast region showing wedge-shaped 
bundles extending from cambium to cortex. 


the seat of complex vital functions and operations involved 
in nutrition, and are much more diversified in form. 
Typical fibres and vessels are represented in Figs. 3—4. 
The arrangement of cells, fibres, and vessels in the stem 
of a plant is co-ordinated with those characteristics which 
determine its position in the evolutionary series. We may 


12 WOOD PULP AND ITS USES 


briefly describe stems which are typical of the two main 
divisions of the highest group of flowering plants. 

Fig. 5 represents a section of the stem of a mono- 
cotyledon. 

These structural types introduce the fundamental con- 
siderations involved in differentiation of tissues; ground 


Jute (mag. 300). 
IIc. 5c.—Section of bast region showing structure of 
bundles and thickening of ultimate fibres. 
tissue, known as parenchyma, is made up of thin naked 
cells showing equality in their dimensions, though occa- 
sionally elongated. The earliest differentiation of the 
eround tissue separates nutritive cells from reproductive 
cells : in the building up of the plant body we are concerned 
with the former only, and their further specialisation 


THE STRUCTURAL. ELEMENTS OF WOOD 13 


is an adaptation to mechanical and physical exigencies 
rather than for vital purposes. The requirements to be 
met are (1) for the transportation of nutritive matter from 
the leaves where it is manufactured, as well as of water 
absorbed by the roots. Hence the provision of con- 
ducting tissue—or mestome; (2) the plant, to maintain 


Fic. 5p.—Section of stem of Linum showing groups of 
bast fibres lying between wood and cortex. 

its form, requires mechanical support, and tissue is 
differentiated into rigid structures known as stereome. 

These features are generally illustrated in the annexed 
figure, showing in section the stems of two dicotyledonous 
annuals, flax and jute, and of a monocotyledonous annual 
Indian corn (Zea Mais). 


14 WOOD PULP AND ITS USES 


They will be better understood after dealing with the 
more complex case of the perennial stem. ‘The forma- 
tion of wood, 2.e., massive wood, is a process which is con- 
cerned with the growth of trees, and although the perennial 
erowth introduces no new structural elements, it does 
present a certain development of plan or arrangement 


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Fic. 6.—Transverse section of stem of Lymnanthemum 
(aquatic plant). Central axis with xylem and 
phloem elements. Ground tissue showing large 
air cells producing buoyancy, and star-shaped idio- 
blasts. 

beyond that of the annual stem. At the outset we notice 
there is a contrast of the dicotyl (or conifer) stem with the 
monocotyl, and since the supply of wood pulp is at this 
date exclusively drawn from wood of the former types, we 
must set out their typical characteristics in some detail. 


The apex of a growing stem exhibits an active condition 


15 


NTS OF WOOD 


\ 


stele, and between them (c) the cortex. 


THE STRUCTURAL ELEM 
of cell division with a differentiation into definite regions, 
(Lymnanthemum, Fig. 6.) 


which becomes more marked as we proceed downwards. 
(a) epidermis, the external protective tissue; (b) the central 


In the finally differentiated stem these are marked out as 


cylinder, or 


wei Maraer 
ht uf ! 
aN 
DEATH RAL 


aye: 


= = —e 
Y A + 
Beare R 


; sat ] olWe 


=45! 


Hepes ; 


f 
! 
aN 

a 
LE HN 


round 


O 
co) 


e bast fibres and 


howin 


eitudinal section of stem of Tila 
S 


), 


Lime Tree 


Huropoea 


F ia. 7.—Transverse lon 
tissue. 


The cortex is complex 


In the perennial stem the epidermis does not keep pace 
with the increasing diameter, and the cortex becomes the 


external protective tissue known as cork, with its well- 


known impervious characteristics. 


in structure. 


16 WOOD PULP AND ITS USES 


It contains active chlorophyllic and assimilating tissue, 
and cells which have a storage function ; also well-marked 


USERERSIS 


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ye Asi 
¥ W 
Cit \ 
; i 
vt 
e 
41 + : 
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mw os fe he 
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iq ‘rag 
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Ate} iY 
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Py dens # - > a - 4 
- Ay i ae eas ee et ; = 4 : ae : 4 
Yo = 
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pe eS a 
—¥ ~ 
i ia a 
SELLE a Re ae gl : ; 
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« 
es, 
— 


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ithe ~~ 
Said 
ie — een 


eire RIFE 


Fie. 8.—-Tangential longitudinal section through the wood 
elements of Tila Huropoea (Lime tree). From left to right 
a medullary ray is seen in the row of little cells, followed 
by typical wood fibres, spiral and pitted vessels, and con- 
nective tissue. 


storage tissues known as collenchyma, or sheathing tissue, 
and sclerenchyma, or hard tissue. The latter is, from the 


THE STRUCTURAL ELEMENTS OF WOOD 17 


present point of view, the more important, as it includes the 
elongated thick-walled cells known as fibres (Fig. 8). In 
the central cylinder, or stele, the vascular tissue is 
prominent (Fig. 7). There are two well-marked types of 
vessels—the trachez, which are of large diameter, with 


Fie. 9.—Longitudinal radial section of Pinus Sylvestris 
timber showing well-developed bordered pits upon 
the walls of the tracheids. At right angles to the 
tracheids is a medullary ray. 


heavy walls variously modified in structure into spiral 
bands, rings, or reticulations (Fig. 8). 

Being destined for water conduction, they are arranged 
end to end in a continuous longitudinal series. In the 
conifer stem there is very large characteristic development 
of the tracheal-like tissue ; but the constituent vessels differ 

W.P. C 


18 WOOD PULP AND ITS USES 


from the true trachee in having tapering ends, and in not 
being disposed in longitudinal series. 

These vessels are called tracheids, and they are charac- 
terised by pitted walls which, under the microscope, appear 
as double concentric rings arranged in rows (Figs. 9 and 
10). The second type of vessel is the sieve tube, so called 


q 
|) 
4 


Fic. 10.—Tangential longitudinal section of old wood 
of Pinus showing tracheids and medullary rays; the 
latter consist of two or more rows of cells arranged 
longitudinally. 


from the specially perforated area which they develop, 
termed the callus plate. They are concerned in the con- 
duction and distribution of organic nutrient matter. 

These two types of vessels are characteristic respectively 
of the xylem or wood, and phloem or bast. In the 
dicotyledonous stem the strands of xylem and phloem, 


THE STRUCTURAL ELEMENTS OF WOOD LY 


though separate, are organised together into vascular 
bundles. The disposition and relation of these bundles are 
the characteristic of the exogenous stem. 

They form a centric system—the xylem towards the 
centre, the phloem towards the periphery. The paren- 
chyma enclosed in the vascular cylinder is the pith or 


a 
Pe 


Fie. 114.—Transverse section of stem of Gossy- 
pium (cotton plant) showing one annular 
ring of xylem and phloem elements with 
intervening cambium layer. 


medulla, and its extensions outwards between the vascular 
bundles are called pith or medullary rays, and act as 
storage cells for reserve food material. 

But the most obvious feature of the transverse section 
of a forest tree, viz., the annual rings, remains to be 
elucidated. 

In the xylem-phloem bundles there is a central portion 

; C2 


20 WOOD PULP AND ITS USES 


of meristematic tissue, which continues the process of cell 
division and differentiation, contributing new xylem on the 
one side and phloem on the other. And further, this active 
tissue, known as cambium, extends from bundle to bundle 
across the pith (rays), assuming therefore a structural ring. 
The annual accretion of new tissue, which is a product of 
the cambium, is thus marked as ina ring. (Fig. 114.) 

As the trunk or stem increases in girth, an increasing 
portion of the xylem ceases to take part in the conduction 
of water, the ascending sap passes through the younger 
tissues or sap wood, which becomes differentiated in colour 
and other aspects from the heart wood; in fact, it is this 
differentiation of the sap wood from the heart wood by 
the formation of vessels, tracheids, and fibres of larger 
diameter and thinner wallsin the former tissues, that serves 
to accentuate the well-marked characters of the rings. 
(Fig. 11s.) The concentricity of the rings varies also in 
different trees; the gymnosperms, for example, are ex- 
tremely regular, whilst in some angiosperms the rings are 
more or less wavy, and in others again, such as the beech, 
the rings are crested. The new phloem deposited in contact 
with the old, causes rupture of the latter, and it pulls or 
scales away more or less rapidly. 

The bark of trees is very complex in structure, very 
variable in character both as regards its structural com- 
ponents and its proportion and massive distribution; 
generally it is not permanently associated with the stem or 
trunk, as are the new wood tissues. ‘This is also in accord- 
ance with our superficial observations of the habits of 
trees. 

The conspicuous feature of the dicotyledonous stem is, 


THE STRUCTURAL ELEMENTS OF WOOD 21 


therefore, the collateral vascular bundle, open in the sense 
that the cambium constitutes a connecting tissue linking 


wat 


iuoaues 


F 


mee 


PLATA 
ais 


Tie 

ra 

Cate 
PS 6 


oe 


* a. 
oe EF 8. 
a 


@ 
= 


Ita. 118.—Transverse section of a three-year-old stem of 
Tilia (Lime Tree). At centre pith then xylem (wood) 
in three separate rings. Towards the periphery 
the cambium ring then phloem and cortical tissue. 


. 


the bundles. In contrast with this, the monocotyledonous 
stem is composed essentially of a ground tissue, and 


. 


22 WOOD PULP AND ITS USES 


scattered but closed fibro-vascular bundles, i.e., with no 
connecting cambium (see Fig. 5). 

This arrangement implies an absence of provision for 
large increase of diameter, and the stem of a perennial of 
this type is columnar or cylindrical rather than conical. 

There is a corresponding lack of provision for developing 
an increase of foliage by way of a system of branches. 
The foliage is thus a crown of leaves, as in the palm 


iG. 12.—Date Palm. Typical Monocotyledon Perennial. 


(Fig. 12), which remains very much the same from year 
to year. (Compare with Figs. 128, 120.) The vascular 
bundles generally develop stereome tissue, 7.e., sclerenchy- 
matous thick-walled fibres which, in association with the 
vessels, constitute the fibres and vascular bundles. 

We have now become aware of the principal structural 
elements of a wooded stem, and we can analyse some of 
the aspects of wood sections which are familiar to us as 
the “ grain.” | 


THE STRUCTURAL ELEMENTS OF WOOD 23 


Usually the xylem elements are parallel to the axis, in 
which case we have the term “straight grain’; but 
irregularities appear in the growth of the various tissues 


Fic. 128.—Pine. Typical Conifer. Exogenous Gymnosperm. 


(1) by a continuation of the growth of the cells after separa- 
tion from the cambium proper, thus causing an interlacing 
of the fibrous elements, with a consequent cross-grain 


24 WOOD PULP AND ITS USES 


effect ; or (2) in the formation of branches and adventitious 
buds, producing the effect known as ‘burr.’ Other 
irregularities are seen in the projections of the xylem 


Fig. 12c.—Oak. Typical Angiosperm Exogenous Perennial. 


elements from the rings, causing the ‘‘ bird’s-eye ”’ effect so 
well marked in the maple. 
In the angiosperms the medullary rays are much more 


THE STRUCTURAL ELEMENTS OF WOOD 25 


highly developed than in the gymnosperms, and constitute 
in some cases a large percentage of the wood. 

In the oak the primary medullary rays may be built up 
of several hundred rows of cells, and when seen in radial 
sections appear as silvery bands, or silver grain, as it is 
termed. 

Some of the poplars frequently have the medullary 
system aggregated together in spots known as ‘“ pith 
flecks,’ which help to identify the species. 

We may note that in addition to the formation of the 
ligno-cellulose or primary plant substance (see p. 57), various 
other products of secretion are formed. Proteins, or nitro- 
genous bodies, carbohydrates, glucosides, resins, and other 
aromatic substances, acids, such as tannic acid, dye stuffs, 
which impart particular characters to the woods, and aid in 
its identification. 


PuysicaL Properties oF Woops. 


Weight.—This depends upon the condition of the wood 
in relation to moisture, and as regards structure, i.c., upon 
the proportion of small heavily lignified vessels such as 
would be illustrated by the ‘‘ heart wood,” this being 
relatively much more dense than the more distended 
vessels of the “ sap wood.” 

The following table illustrates the density of various 
woods :— 


Wood. Density. 
Very light Poplar 0°26 0°4 
Light Spruce and Pine 0°4 0°6 


Moderately heavy Birch and Beech 0°6 Wea 
Heavy Oak 0°8 and upwards 


26 WOOD PULP AND ITS-USES 


Hardness.—This is usually measured in terms of the 
number of kilograms required to force a punch of 1 sq. em. 
in area to a depth of 1°27 mm. into the wood, perpen- 
dicular to the direction of the fibres. 

The following table illustrates the relative hardness in 
decreasing proportions :— 


Hardness in 


Wood. kilograms 

per sq. cm. 
Lignum Vite . 793 
Oak : : ; : : : 225 
Beech . ; 200 
Most coniferous woods. ; 100 


Cotton tree Bombax Malabaricum — - — 
(type of softest wood) 


Strength of Woods.—This may be defined as the resistance 
offered by the wood to any force tending to break the fibres 
across (transverse stress), or to overcome the cohesion of the 
fibres (longitudinal stress). 

In the testing of woods various other stresses are applied; 
but the breaking strain, as stated above, is by far the most 
important. 

It is found that in broad-leaved trees the lateral resistance 
is from 2th to 4th of the longitudinal resistance, and in 
the coniferous 35th to ;4th. 

Tetmayer of Zurich has arranged in the following table 
the relative resistance of the woods to various stresses :— 


Transverse 
Pressure. Tension, Crushing. Shearing. 
Beech Beech Oak Beech 


Oak Oak Beech Oak. 


PHYSICAL PROPERTIES OF WOODS 2 


~I 


Transverse 


Pressure. Tension. Crushing. Shearing. 
Larch Scotch Pine Larch Larch 
_ Silver Fir Larch Silver Fir Spruce 
Spruce Spruce Spruce Silver Fir 


Scotch Pine Silver Fir Scotch Pine Scotch Pine. 


It was found that Scotch pine had the lowest technical 
value, silver fir 20 per cent. greater, spruce 26 per cent. 
creater, larch 66 per cent. greater, oak beech 95 per cent. 
greater. 

Two other factors usually determined in wood are (1) the 
ash, that is the amount of inorganic constituents left after 
burning the wood, which is a small proportion by weight 
though voluminous ; (2) the calorific, or fuel, value of the 
wood. On an average it is found to be about 4,000 
calories or heat units, in other words, one unit of weight 
of dry wood on burning furnishes heat which would raise 
4,000 units of weight of water 1° C. 

The foregoing brief exposé implies the fundamental con- 
ditions of fitness of a given wood or wood substance for 
conversion into a fibrous raw material. These are primarily 
a large proportion of elongated cells or fibre, and, as the 
basis of economic production of such pulps, it will be 
obvious that the massive perennial stem fulfils essential 
industrial conditions of growth, transport, and treatment 
for conversion into pulp, which result in low cost of 
production. 

The processes of pulping to be dealt with in a subsequent 
chapter, are of two kinds: (1) a simple disintegration by 
wet-grinding, toa ‘‘ mechanical” pulp. Such pulps are sub- 
stantially the original wood substance, deprived incidentally 


28 WOOD PULP AND ITS USES 


of water-soluble constituents (see p. 97); (2) chemical 
processes which attack the igneous constituents and convert 
them into soluble derivatives, leaving the cellulose which 
preserves the form and dimensions of the original fibres 
constituting a ‘‘ chemical” pulp composed of the fibrous 
structural elements of the wood in the fully resolved 
condition (see p. 120). 

The number of woods fulfilling what is a very exacting 
specification of requirements, is extremely limited. Actually 
the wood pulp industry is based upon the utilisation of 
coniferous woods and poplar. 


CHAPTER II 


I. CELLULOSE AS A CHEMICAL INDIVIDUAL AND TYPICAL COLLOID. 
II. THE LIGNONE COMPLEX, LIGNO-CELLULOSE; SPECIAL 
CHEMICAL NOTE ON AUTOXIDATION, AND RESEARCHES OF 
W. J. RUSSELL 


THE investigation of the nature and composition of the 
woods is a problem of “ organic chemistry.’ The wood 
substance is in all cases a complex of carbon compounds. 
The woods present variations in composition which are 
definite and characteristic; but these are only minor 
divergences from a common type. As representative of 
the type we may take two individuals. 

The jute fibre—the lignified bast fibre of an annual, a 
simple tissue—and beech-wood, which represents perennial 
growth, and from its nature is an assemblage or mixture of 
structural elements. 

We have in the previous chapter spoken of “‘ lignification ” 
as a process. Morphologically it is a process of thickening 
by incrustation, and according to recent researches this 
incrustation is a process of forming adsorption com- 
pounds, the colloidal hydrated celluloses first elaborated, 
taking up soluble colloidal products from solution in the 
cambium fluids or “ sap’’ (A. Wislicenus, Zeitsch. Kolloide, 
1910, p.17); chemically it is regarded as the formation ofa 
cellulose derivative by combination of cellulose with 
certain acid and unsaturated ketonic groups, the resulting 


30 WOOD PULP AND ITS USES 


compound or complex being a ligno-cellulose. Conversely, 
by various processes which attack these acid and unsaturated 
groups, the ligno-cellulose is resolved into derivatives of the 
latter which are soluble, and cellulose which is resistant 
and insoluble. ‘The separation or isolation of cellulose is 
attended by disintegration; the aggregated structure is 
resolved into its component units, which are cells, including 
in this general term fibres and vessels. In the ligno- 
celluloses these are of small dimensions, 2—38 mm. in 
length, and ‘02—-03 diameter. A mass of such units in 
contact with water constitutes a ‘‘ pulp.” The separated 
cells retain their dimensions and general structural 
characteristics notwithstanding that the elimination of the 
non-cellulose components is attended by considerable loss 
of substance, z.e., weight, and the cellulose may therefore 
be regarded as the more permanent skeleton or framework 
of the cell. The quantitative relations of this resolution 
are of importance. The following percentage numbers 
characterise the typical ligno-celluloses :— 


Cellulose. Lignone. 
Jute . : : (050 pe : 30—20 
Beechwood ‘ 50—60 . . 50—40 


It may assist the student in estimating the practical 
significance of these chemical facts to point out that a 
ligno-cellulose is related to cellulose somewhat in the same 
way asan alloy of gold with baser metalsis to gold. Goldas 
a “noble metal’ is relatively non-reactive, and especially 
distinguished by resistance to oxygen, and is therefore 
permanent in the air and generally unaffected by the 
conditions which prevail on the earth’s surface. Cellulose 


CELLULOSE AS A CHEMICAL INDIVIDUAL 31 


is resistant to oxygen and water, and is permanent under 
the prevailing conditions of our planet. A gold alloy is 
amenable to the attack of oxygen which combines with the 
constituent metals, converting them into oxides, or of 
reagents which dissolve the baser metals as salts: the gold 
is left as elementary metal. Similarly, cellulose is obtained 
as aresidue resisting the action of reagents such as chlorine, 
caustic alkalis or bisulphites, all of which combine 
directly with the lignone groups, for reasons which will 
appear. 

It would take us outside the scope of our present treat- 
ment of the subject to attempt an exhaustive exposé of the 
chemistry of these natural products. The special outline 
which we give may be regarded as the irreducible minimum 
necessary as the foundation of the chemical technology of 
the subject. We have already implied that the woods are 
modified celluloses, from which their more important 
constituent, that is the cellulose, is readily isolated. 

Cellulose is a carbohydrate ; it 1s derived from the sugars 
and under severe treatment may be resolved into sugars. 
Its ultimate composition is represented by the formula 
n(CgHi0s), and, in breaking down to the simplest sugar, 
CgH120¢ the process may be formulated as one of simple 
“hydrolysis”: n(CgHi005) + nH2O = nCegHi20¢. But of 
the mechanism of this resolution we are profoundly 
ignorant. Indeed, it cannot be said that the above equation 
of hydrolysis has been verified experimentally. Recent 
researches of H. Ost and L. Wilkening (Chem. Zeit., 
1910, 34, 461), establish a conversion of cellulose into 
fermentable sugars to the extent of 90 per cent. of its 
weight, with a residue of acid products. The above equation 


32 WOOD PULP AND -ITS USES 


is therefore not more than an approximate picture of the 
underlying facts. This is equivalent to the statement that 
we are entirely ignorant of the actual constitution of 
cellulose. 

We are more familiar with another complex carbohydrate, 
starch, which has a similar empirical formula n(CgHy00s). 
Starch is quantitatively resolved into the sugars, maltose 
and dextrose, by hydrolytic action determined by reagents 
or by ferment actions and under conditions which enable 
us to follow minutely the stages of the transformation. 
These reveal the extreme complexity of the aggregate which 
constitutes starch. But although we can closely follow this 
chemical disintegration through its stages, we are unable to 
integrate these results of analysis into a formula, still less 
by any laboratory process to reascend the scale and trans- 
form the products of resolution back to starch. A fortiori, 
the proximate constitution of cellulose is problematical. 

Starch and cellulose are not only closely linked by many 
analogies which have been established by comparative 
investigation in the laboratory, but in the plant they stand 
in intimate, in fact genetic, relationship, as evidenced by 
the transformation from one to another, and the equivalence 
of their vital functions in many respects. Premising these 
relationships, we may state that the ultimate component 
sroups of cellulose are those of the carbohydrates generally 
and of the sugars in particular—ie., saturated compounds 
and derivatives of polyhydric aleohols—generally resistant 
.e., non-reactive. But the special chemistry of cellulose 
has to do with the complex or aggregate. ~The particular 
feature of cellulose is that it enters into a number of 
reactions, combining with other bodies to form highly 


CELLULOSE AS A CHEMICAL INDIVIDUAL 30 


characteristic derivatives, in which the essential properties 
of the aggregate are fully maintained. These properties 
are recognised in the following: (a) the colloidal character- 
istics of the solutions of the original cellulose, as of its 
ethereal derivatives; (b) the structural characteristics of 
the solids obtainable from these solutions by elimination of 
the solvent; (c) the weight relations of the products, the 
cellulose maintaining its integrity as a complex. What we 
have to set forth as a sketch of the special properties of 
cellulose will follow this order of, idea. 


rh 


Cellulose as a Typical Colloid.—lt may be said generally 
that we know very little of solid substances; it is only in 
solution or the fluid state that matter lends itself to quanti- 
tative analytical investigation. It is in the manifestation 
of associated properties in solution that compound matter 
has come to be regarded as falling into two great divisions, 
Crystalloids and Colloids. Crystalloids are crystalline as 
solids and when dissolved in neutral solvents constitute 
limpid solutions; Colloids are non-crystalline or amorphous, 
and dissolve to viscous or gelatinous solutions. On evapo- 
rating the solvent the former resume their crystalline form, 
the latter constitute structureless masses; these may be 
transparent, and if spread over a relatively large superficial 
area they take the form of a film or sheet. A familiar type 
of colloid is gelatin. Gelatin in 10—20 per cent. aqueous 
solution at temperatures of 50—100°, is a viscous liquid ; 
the solution on cooling to 20—30° solidifies to a jelly or 
‘“oel.” The “ gel” continues to lose water at its surface 
and, by withdrawing water from the interior, continues the 
process-of desiccation. The “air dry ”’ solid finally retains 

W.P. D 


34 WOOD PULP AND ITS USES 


15 per cent. of its weight of moisture, which requires a 
higher temperature for its expulsion. The dry solid is 
relatively inelastic or brittle. 

There are various views current as to the causes under- 
lying these phenomena. Any such view or “theory of the 
colloidal state’ must set out from the observed experimental 
facts which are, chiefly: (1) The antithesis between solid 
crystalline and amorphous matter; (2) the correlatively 
divergent properties of these two types of matter when in 
solution: thus, the crystalloids are generally electrolytes : 
they are conductors of the electric current, by which they 
are readily decomposed, taking up the electrical energy and 
splitting into polar constituents ; the colloids are non-con- 
ductors in this sense. The crystalloids are diffusible, 1.e., 
they readily pass through membranes such as parchment, 
or parchmentised paper—the phenomena being classified 
under the term osmosis ; the colloids are not diffusible— 
that is, exert no osmotic pressure in solution—and conse- 
quently are not transmitted through such membranes or 
films. 

The crystalloids, in dissolving, undergo changes of volume, 
accompanied by considerable thermal effects: the colloids 
dissolve with relatively sight volume change. Colloidal 
matter, when observed in transparent forms, is optically 
homogeneous ; crystalline matter exhibits selective actions 
which are classified under the term polarisation. These 
effects in certain groups of compounds, e.g., the sugars, 
persist in their solutions. It is important to note that we 
have the primary antithesis of solid form, associated with 
differentiated relationships to the various forms of energy— 
electricity, heat‘and hght. It must not be assumed, how- 
ever, that there is any sharp distinction of one form of 


CELLULOSE AS A CHEMICAL INDIVIDUAL 35 


matter from another: the antithesis is an opposition of 
extremes, emphasised by the comparison of typical repre- 
sentatives. But these extremes graduate on either side 
into forms of matter which have the characteristics of both. 
There is an important deduction from these relationships, 
which is that throughout the series the ultimate properties 
of matter are involved as the conditioning factor of the 
“physical” state. It was formerly held that the antithesis 
of crystalloid and colloid was of “‘ physical”’ significance 
only, that is, depended rather upon proximate relationships 
than upon the ultimate properties of matter, which are 
‘chemical.’ We cannot pursue this theme at any length, 
and we must refer students who aim at more fundamental 
analysis of phenomena to special treatises, instancing more 
particularly ‘‘ Neue Gesichtspunkte zur Theorie der Kol- 
loide”’ (EK. Jordis, Erlangen, 1904), and other critical and 
experimental contributions which connect the properties of 
colloids with the modern theory of solutions. As a general 
text book we need only mention “ Grundriss der Kolloid- 
chemie,” by W. Ostwald (Dresden, T. Steinkopff). For a 
general résumé of the literature of colloids covering the 
earlier periods, the ‘‘ Bibliographie der Kolloide,” by 
A. Muller (Leipzig, 1904, L. Voss), and for present develop- 
ments the scientific serial ‘‘ Zeitschrift fiir Chemie und 
Industrie der Kolloide”’ (Dresden, Steinkopff). As a 
general review of the chemistry of cellulose considered as 
a typical colloid and tlie probable relationships of its 
colloidal characteristics to chemical constitution, the 
student may consult ‘‘ Researches on Cellulose,”’ IT. (1906), 
Cross and Bevan. 

Cellulose is itself insoluble in all neutral solvent liquids. 

D 2 


36 WOOD PULP AND ITS USES 


¢ 


The ‘solutions of cellulose’ are in all cases solutions of 
derivatives. There are two main groups of these deriva- 
tives :— 

(a.) Colloidal double salts of cellulose with metallic saline 
compounds, viz., zinc chloride and cuprammonium. A 
“solution of cellulose’? results from digestion with these 
reagents in aqueous solution, and the cellulose is separated 
from. these solutions by mere dilution. It is obtained in 
a gelatinous, hydrated, and of course, structureless form. 
The precipitated cellulose retains the metallic oxides; but 
these are readily removed by treatment with acids. The 
solutions have a high viscosity and the limit of fluidity, for 
the purpose of the practical applications of these solutions 
is reached when the percentage of cellulose in solution is 
5—7. Higher percentages in fluid solution are attained at 
the expense of the integrity of the cellulose aggregate, that 
is, by various processes of hydrolysis; thus, by employing 
with the zine chloride various and increasing proportions 
of hydrochloric acid, or by previous treatment of the 
cellulose with both acid and basic reagents, which resolve 
the aggregate by hydrolytic actions. It must be noted that 
the state of disintegration of the aggregate persists in the 
reverted product; the cellulose recovered from the solutions 
by precipitation is more or less degraded in its structural 
properties. 

(b.) The esters of cellulose are the derivatives which 
result from the combination of its OH groups with acid 
radicals. The most important of these are the Nitrates, or 
30-called Nitrocelluloses, the Acetates and Benzoates. The 
Benzoates are of no practical (2.e., industrial) importance. 
The Nitrates and Acetates are formed by the action of the 


CELLULOSE AS A CHEMICAL INDIVIDUAL 37 


acids or their anhydrides upon cellulose. The “ nitration ”’ 


> 


or “acetylation”? is progressive, and to form derivatives 
soluble in various neutral liquids the degree of esterification 
must proceed beyond a certain limit, viz., that represented 
by the combination of two of the OH groups of the unit 
CgHwO05. Actually the derivatives most commonly employed 
are, in the case of the nitrates, the esters intermediate 
between the dinitrate and trinitrate; in the case of the 
acetates, the complete solubility of the ester requires a 
stage of esterification closely approximating to the produc- 
tion of a triacetate. 

The solvents employed are in the case of the nitrates, 
ether-alcohol, alcohol and camphor, ethyl-acetate, ace- 
tone, and variations of these. The acetates are soluble in 
a more limited range of liquids, of which chloroform is the 
most important and characteristic; other solvents are 
acetic acid, phenol, and pyridine. It is important to note 
that these esters are produced with a necessarily large 
increase of weight of the product as compared with the 
original cellulose, resulting from the introduction of the 
relatively heavy acid or negative group. ‘This will be 
appreciated from inspection of the equations representing 
the limiting reactions thus :— 


Cellulose. Nitric Acid. Water. Cellulose Trinitrate. 
Ce Hi00; + 3 HNOs = 3 H.O + CelH,O2 (NOs) 
162 (3 x 68) (3 x 18) 297 

Cellulose. Acetic Acid. Cellulose Triacetate. 
CgHi190; + 3 C.H40. — 3 H,O + CeHOs (CgH302) 


162 (3 x 60) (3 x 18) 288 


38 WOOD PULPOAND “ITs USES 


an increase of weight in either case of over 75 per 100 of 
cellulose. 

These combinations, involving such large increases of 
weight, may take place under regulated conditions, without 
affecting the structural integrity of the fibre; the esters 
differing but little in external appearance from the original 
cellulose. 

They now dissolve in their respective solvents to 
structureless solutions, which are fluid at concentrations of 
10—15 per cent. of the ester. It is to be noted from the 
weight relationship above set forth that these concentrations 
are in their equivalent of cellulose 6—8 per cent. 

From these solutions the esters are recovered unchanged, 
by evaporation of the solvent, or by removing it by the 
action of a liquid, which mixes with the solvent but is not a 
solvent of the cellulose. From the esters so recovered, the 
cellulose can only be regenerated by the chemical process 
of saponification, that is, by the attack of certain alkaline 
agents which combine with and remove the combined acid 
eroups and restore the OH groups of the original cellulose. 

In the industrial uses of these compounds they are 
sometimes employed as such, or as in the production of 
artificial silk, the solution being drawn or spun through 
fine orifices and solidified to the artificial thread which in 
the case of the nitrate is then denitrated or saponified to 
cellulose. 

The industrial process is therefore in the latter case a 
complete chemical cycle; the ester stage being, for all 
practical purposes, merely a solvent-plastic condition of the 
cellulose. 

(c.) Intermediate between these two groups and combining 


s 


CELLULOSE AS A CHEMICAL INDIVIDUAL 39 


their essential features, is the derivative known as the 
sulpho-carbonate, or in solution, as viscose. ‘This is a 
water-soluble ester of cellulose, formed by treating cellulose 
with strong solutions of the alkaline hydrates, e.g., caustic 
‘soda, and the compound so obtained, or alkali-cellulose with 
carbon bi-sulphide. ‘The ester is thus synthesised in the 
two stages, and its final form is the sodium salt of cellulose- 
xanthogenic acid, a compound freely soluble in water. 
The aqueous solutions of these derivatives (viscose) are 
structureless, and at cellulose concentrations of 8—12 per 
cent., are sufficiently fluid for manipulation through filters 
and for passage through fine orifices under small pressures. 
(See p. 247.) 

The reaction which produces these compounds is a 
reversible one, and the solutions, on standing, spontaneously 
revert to cellulose by dissociation of the alkaline sulphur 
residues. ‘The cycle of synthesis and decomposition may 
be represented by the subjoined diagram :— 


Synthesis. 
Alkaline hydrate Solution of 


-—_)y Xanthogenic Hster. 
4 Carbon Bisulphide | 


430% _ Viscose. 
oe 
goon 
yee 
-Carbon-disulphide 
' Alkali and products of and Cellulose (Hydrate) 
interaction 


Cellulose 


Upon these fundamental facts are based a number of 
important industrial applications of cellulose. 


40) WOOD PULP AND ITS USES 


In the preceding section we have indicated that the 
cellulose in the form of these soluble derivatives is a 
structureless colloid. In the plastic condition it may be 
made to take any desired form, and it is produced indus- 
trially in filament or thread, in film or sheet, or, lastly, in 
massive solids of any required dimensions. ‘The special 
feature of these artificial forms is a particular continuity of 
substance. In passing from the state of solution to the 
ultimate solid form there are no breaks in this continuity, 
and the structural characteristics of these artificial forms 
are conditioned by this fact, which, in turn, rests upon the 
ultimate constitution of the cellulose substance or matter. 
This finally must be held to be intimately associated with 
its typically colloidal properties. 

The practical effects or consequences of these constitu- 
tional properties are seen in the qualities of resistance of 
the derivative solids. The mechanical properties of the 
artificial threads, which are expressed in terms of tensile 
strength or tenacity, extensibility (elasticity), are essential 
factors of their textile applications. These properties are 
compared and brought to numerical expression in various 
ways: thus the tenacity 1s measured in terms of the 
maximum weight which the thread will support. As an 
average figure we may take this as 8,000—9,000 grms. 
per square millimetre of section. Another mode of 
expression of the physical fact is in terms of ‘‘ breaking 
length,” that is, the length of the particular fabric repre- 
senting such breaking weight. Elasticity is the maximum 
elongation of the thread under strain from which it will 
revert to its original dimensions when the strain is 
removed. This may be 2 to 8 per cent. Extensibility is 


CELLULOSE AS A CHEMICAL INDIVIDUAL 41 


the elongation of the thread when strained to its breaking 
point. This varies from 10 to 20 percent.t These cellulose 
threads are known as “ artificial silks,’ and it is evident 
from the term, that they are applied to similar purposes as 
the natural silks. It is of interest, therefore, to compare 
these products in regard to their fundamental mechanical 
properties. We quote from a paper on ‘‘CelHulose and 
Chemical Industry’ (Cross and Bevan, Jowrn. Soc. Chem. 
Ind., 27, 1908). 

The comparison with silk is direct and simple, since both 
represent amorphous colloidal matter or substance. 

The artificial silks may be taken as showing the following 
range of textile quality :— 


Gramme. 


2 Breaking strain or tenacity per unit denier. 1-0—1°4 
Extensibility under breaking strain } : 159% == 17% 
True elasticity . ; : ; : : 4% —5% 


The corresponding averages for the true silks (in the 
boiled-off state) are :— 


Breaking strain or tenacity perdenier : 2°0—2°5 
Extensibility under breaking strain . ; 15%—25% 
True elasticity . ; : : ; 4%—5% 


Strehlenert has established the following relationships, 
which are important (Chem.-Zeit., 1901, p. 1100). 

The breaking lengths are expressed in terms of kilo- 
erammes per square millimetre of section, which is a 


' These points are further elucidated in Chap. X. 
2 Denier is the unit weight/length : mgr. per 10 metres. 


42 WOOD PULP AND ITS USES 


satisfactory basis of comparison in view of the close 
structural similarity of the products investigated :— 


Dry Wet. 
China raw silk P ; : : : 53°2 46°7 

Hrench., 4; : : ‘ : : 50°4 40°9 

“Natural var bolledrol ; : ; $ 25°5 13°6 
“cake oy fo dyedired, weighted ae 20°0 15°6 
silk. ,, blue black at 110 per cent. : 1294 80 

5 Ss =) 140 per cent. mee iS, 6°3 

¥ 4h a 500 per cent. ; pb — 

*¢ Artificial ( Chardonnet wi rates : 14°7 La 
silks.” Lehner nas aaa Lea 4:3 
Lustra Glanzstoff, cuprammonium process : 19°1 3°2 
celluloses \ Viscose, xanthate process : : : Bina 673 


The lustra celluloses are thus inferior in tenacity to 
the silks, but when these are ‘“ weighted” there is a 
loss of strength beyond that which would be directly 
proportional to the degree of ‘‘dilution” of the silk 
substance. 

As the weighting of silks is very largely practised, it 
will be seen that the lustra celluloses are quite on the 
average level of textile quality, even in this higher 
sphere. 

In regard to elasticity and extensibility, which are 
important correlative measures of textile quality, a similar 
series of relations obtains. 

The lustra celluloses, on the other hand, have a special 
relationship to water, the colloidal cellulose having a con- 
siderable hydration capacity. In actual practice this fact 
is not of such moment as to impede the very rapid progress 
of the industry in these new textiles. 

That this property or relationship of the cellulose is 
modifiable appears to be a reasonable deduction from the 


CELLULOSE AS A CHEMICAL INDIVIDUAL 43 


general reactivity of cellulose. It has been presumed by 
investigators that the cellulose (hydrate) is susceptible of 
modification, either by intrinsic or constitutional change, 
or by reaction to form a new derivative, in such a way as to 
yield a product more nearly resembling the normal cotton 
cellulose in resistance to hydration. At this date there is 
only one method which has given promise of industrial 
results in this desirable direction. 

The cellulose, notably in the form of artificial silk, is 
treated with formaldehyde in aqueous solution containing 
also auxiliary agents determining combination. 

As a result of the combination it appears there is some 
constitutional change in the cellulose itself accompanying 
the fixation of the H,CO groups, and this suggestion 1s of 
moment, as it indicates a capacity of internal structural 
modification which offers an attractive field for research. 

It is of particular interest to note that the artificial silks, 
though produced by treatments of cellulose presenting the 
widest contrasts in chemical and physical conditions, are 
closely similar in their properties. It is evident from this 
that though cellulose is, in chemical language, extremely 
labile, it is nevertheless so constituted as an aggregate as 
to be equally stable, or resistant to change. 

The reversion of cellulose or of its esters from the 
solutions above enumerated, in the form of film or sheet, 
introduces no novel features of the product. ‘The qualities 
of the film which condition its industrial employment are 
tensile strength and elasticity. 

In the production of solids in massive forms, a number of 
factors are introduced with the exaggeration of the third 
dimension, and only one of the solutions, viz., viscose, 


44 WOOD PULP AND ITS USES 


lends itself to the production of cellulose products of this 
order. The nitrate solutions which are the basis of the 
highly important celluloid industry area plastic form of the 
nitrate or cellulose ester, and the forms into which it is 
fashioned while in the plastic state are but little different in 
dimensions from those of the permanent and rigid solids 
into which they pass by evaporation of the solvent. 
These are constituted of the unchanged nitrate or cellulose 
ester. No economical method has been devised for turning 
out the acid groups from the ester in these massive forms 
and thus arriving at cellulose in corresponding forms. But 
the viscose solutions in spontaneously reverting to cellulose 
and solidifying may be cast, at this stage, into any desired 
form. ‘The masses so obtained are composed of the cellulose 
in a much hydrated state ; but though retaining nine times 
its weight of water (of hydration) it has, nevertheless, a con- 
siderable mechanical resistance. Permeated as it is with 
the alkaline-sulphur by-products, it requires exhaustive 
washing to remove them. ‘The purified mass of hydrated 
cellulose, if now dehydrated and desiccated by exposure to 
the atmosphere, parts with its water continuously and 
progressively, shrinks upon itself, and finally, is obtained 
in transparent or translucent masses. The cellulose solid 
so obtained is an extremely resistant material. 

The properties of this material may be compared with 
those of other solids used in construction, and it will be seen 
to have qualities of a very high order. 

Lastly, we have to call particular attention to the 
facts which have been generally noted as regards the 
weight relationships of these cycles of transformations. 
Taking the two extreme cases, that is, with the widest 


CELLULOSE AS A CHEMICAL INDIVIDUAL 45 


divergence of the conditions of reaction and with reference 
to the same unit of cellulose, which we may conveniently 
take at 100 parts by weight: 


Cyclea. Cellulose. Nitrate. Cellulose (hydrate) Acid. 


One hundred parts of cellulose combine with nitric acid 
(with elimination of water) becoming 165 parts of cellulose 
nitrate, dissolved in alcohol-ether to 15 per cent. solution 
(equivalent to 9 per cent. cellulose) and spun to thread, 
denitrated with ammonium-magnesium sulphydrate, and 
reverting to 103 parts by weight of cellulose hydrate. 


Cycle 6. Cellulose. Xanthogenic Ester. Cellulose hydrate. 


Alkaline. 


One hundred parts of cellulose combine with 50 parts 
sodium hydrate (in presence of water), the alkali ceilu- 
lose reacts with 50 parts disulphide, giving 130 parts of 
cellulose-xanthate of soda dissolved to 13 per cent. 
solution, equivalent to 10 per cent. cellulose, drawn or spun 
into ‘setting ’’ solutions (see p. 246), which decompose the 
ester and regenerate cellulose, yielding 103 parts by weight 
of cellulose (hydrate). 

In either case, therefore, the cycle is completed without 
loss of substance by the cellulose: there is a slight gain 
due to combination with water. 

This is only strictly true of the normal cellulose, which 
is represented by the fully purified cotton fibre. Other 
celluloses, notably wood-celluloses, sustain a loss of weight 
due to conversion into permanently soluble derivatives, 
which may amount to 10—20 per cent. Reciprocally, the 


46 WOOD PULP AND ITS USES 


viscose cycle becomes a constitutional criterion, a normal 
cellulose being one which sustains this cycle of reactions of 
synthesis and decomposition without loss of substance. 

These experimental facts define cellulose as a typical 
colloid. It has, of course, long been recognised in general 
terms that cellulose in its “‘ organic’ forms must be classi- 
fied as a colloid. But the colloidal state having become a 
definite objective of investigation, it is evident that the 
investigation of cellulose through its compounds and deri- 
vatives is destined to contribute considerably to the develop- 
ment of the general theory of the colloidal state. For this 
reason, added to the fact that all the industrial applications 
of cellulose specially involve its colloidal characteristics, we 
have limited our present treatment of the subject to this 
particular aspect. 

We now give a brief systematic résumé of the BrOperaee 
of cellulose as a chemical individual, these tyyical charac- 
teristics being those of cotton cellulose. 

CELLULOSE.—Generally the non-nitrogenous skeleton of 
vegetable tissues. Type: the fibre-substance of cotton, 
purified from associated ‘‘impurities’’ by processes of (1) 
alkaline hydrolysis and oxidation (bleaching) ; (2) of 
digestion with hydrofluoric acid, etc., to remove mineral 
impurity. 

(C 44:4) 

Composition.—Hlementary ; H 6°2; whence the empiri- 

( O 49°4 
eal formula Cg.H 400s. 

Constitution undetermined. Is variously regarded as :— 
Aldose, 


(1) Polyhexose (anhyd ride)<k otose, 


ly 
CELLULOSE AS A CHEMICAL INDIVIDUAL 47 


(2) Polyeyclohexane derivative. 

(3) An aggregate of groups of variable and undetermined 
dimensions, of which only the ultimate terms are known, 
viz., CH,OH, CHOH, CO; but the anhydride forms of the 
alcoholic OH groups, and the position or positions of the 
CO groups remain undetermined. 

Constitutional moisture is retained by the cellulose in its 
air-dry state, varying between 6 and 8 per cent. according 
to temperature and saturation of surrounding air. 

Solvents.—Cellulose is insoluble in all neutral solvent 
liquids. Is dissolved by 

(1) Concentrated solutions of zine chloride on heating at 
80° to 100°. 

(2) Solution of zine chloride (1 part) in concentrated 
hydrochloric acid (2 parts) in the cold. 

(3) Solution of cupric oxide (hydrate) in aqueous 
ammonia in the cold. The cellulose may be recovered 
quantitatively from these solutions, though constitutionally 
changed. 

Reactions.—The above reactions resulting in solution of 
the cellulose are characteristic ; otherwise it is exception- 
ally non-reactive. By dilute solutions of iodine, in presence 
of certain dehydrating agents, it is coloured blue. 

CELLULOSE COMPOUNDS, 1.e., SYNTHETICAL DERIVATIVES. 
—Hsrters (a) Nirrates.—By direct reaction with nitric acid, 
usually in presence of sulphuric acid, in which case unstable 
mixed esters are formed as a stage in the reaction, the 
NOs displacing the SO,H residues. The esters are formed 
without sensible structural modification. They are purified 
from residual SO4H by prolonged boiling with water, and 
are then ‘ stable.’ A series of these esters are known, the 


48 WOOD PULP AND ITS USES 


highest approximating to the trinitrate (Cs) (gun-cotton) 
the intermediate terms—dinitrate—being soluble in ether- 
alcohol (collodion cotton), the lowest having physical pro- 
perties but little different from the original cellulose. 

These esters are variously formulated as nitrates of a 
reactive unit of Ce—Cj.—Co, dimensions. 

Solvents.—The special solvents of these esters are acetone, 
ether-alcohol, nitrobenzene. 

Saponification.—By certain alkaline and reducing agents 
(alkaline sulphydrates) the nitric groups are eliminated and 
cellulose regenerated. 

(b) AcrratEs.—By reaction with acetic anhydride under 
various conditions: (1) at 110° direct formation of mono- 
acetate (Cg) insoluble in all neutral solvents and in the 
solvents of cellulose. (2) At 140° to 160°, formation of 
higher acetates, attended by solution in the reaction mix- 
ture. (3) In presence of catalytic agents (ZnCle—H2SO.w— 
H3PO,4) at intermediate temperatures ; H.SO, determines 
reaction at 25° to 35°. The products are usually mixtures 
of tri- and tetracetate. (4) When the reaction mixtures 
are diluted with hydrocarbon the fibrous cellulose may be 
acetylated without solution or sensible structural change. 

Solvents of the higher acetates, chloroform, acetone, 
phenol. | | 

Saponification.—The acetyl groups may be removed by 
boiling with alkaline solutions, the cellulose being regene- 
rated. In quantitative determinations the saponification 
may be effected by digestion with normal sodium hydrate 
diluted with an equal volume of alcohol. 

(c) Actp-SutpHuric Esters.—By the action of sulphuric 
acid an extended series of esters is formed, which have been 


CELLULOSE AS A CHEMICAL INDIVIDUAL 49 


described as cellulose sulphuric acids. But they are 
certainly derivatives of products of resolution. The first 
stage results in the formation of a disulphuric ester 
CgHgO3 (SOuH)s, but its relationship to the parent complex 
is doubtful. The ester is soluble in water; the Ca, Ba, and 
Pb salts are insoluble in alcohol. Byprogressive hydrolysis 
the cellulose is ultimately resolved to dextrose. 

(d) AceTo-SULPHATES AND Mixep Esrers, containing 
the SO,H residues associated with acetyl and other negative 
sroups in combination, are obtained when sulphuric acid is 
allowed to act under regulated conditions simultaneously 
with other esterifying agents. Thus a mixture of acetic 
anhydride (50 parts), glacial acetic acid (50 parts), and 
sulphuric acid (4 to 6 parts) acts rapidly at 30° to 40°. The 
first product appears to be a neutral body of the empirical 
formula, 

(4 CeH7O)SO.(CoH302)10, 
and under the action of water to undergo an internal 
hydrolysis, the SO. group becoming SO.H, which forms a 
stable combination with bases. The Mg, Ca, Zn salts are 
insoluble in water, but. soluble in acetone (see p. 287). 

(e) Benzoates result from the-action of benzoyl chloride 
in presence of alkaline hydrates. A monobenzoate (Cg) is 
obtained by treating cellulose with a solution of sodium 
hydrate of 10 per cent. (NaOH) strength, and shaking with 
benzoyl chloride. This benzoate is formed with only slight 
structural change. The dibenzoate (C.) is obtained by the 
interaction of benzoyl chloride and alkali-cellulose (mer- 
cerised cotton) in presence of sodium hydrate solution (15 
per cent. NaOH). Its formation is attended by structural 
change ; the fibrous cellulose is disintegrated, the dibenzoate 

W.P. E 


50 WOOD PULP AND ITS USES 


being an amorphous substance. The dibenzoate is soluble 
in acetic acid, chloroform. 

Mrxep Esrers, containing the benzoyl and nitric residues, 
result from the action of nitric acid upon the benzoates. 
Simultaneously a nitro-group enters the benzoyl residue. 

ALKALI CetuuLose.—The fibrous cellulose undergoes con- 
siderable structural modification under the action of solutions 
of sodium hydrate of 12 to 25 per cent. NaOH. ‘There isa 
definite synthetical reaction in the ratio CgHj0;: 2 NaOH, 
which is a stage in the formation of the dibenzoate (supra). 

The compound is completely dissociated by water: by 
treatment with alcohol an equilibrium is reached when the 
reagents are associated in the ratio Cy.HaO0~NaOH. 

The alkali-cellulose hydrate, of composition 


Cellulose , 30 \ . 
Sodium hydrate . 15 { Cellulose: Sodium hydrate, 
Water . : ; oA CeHi00s 2 NaOH 


is the first stage in the synthesis of cellulose xanthogenic 
acid, which results from the interaction of the alkali cellulose 
and carbon disulphide at ordinary temperatures. The 
sodium salt is soluble in water. Itis an unstable compound. 
the solution undergoing spontaneous progressive change. 
The solution, which is highly colloidal, finally solidifies. 
By reason of the characteristic reaction of the xanthates 
with iodine, 
OX XO OX — XO 


CS CS + I, = 2NalI + CS< »CS, 
SNa NaS S S 


the progress of the change may be followed, the essential 
feature being the elimination of the CS, residues with re- 


CELLULOSE AS A CHEMICAL INDIVIDUAL dl 


ageregation of the cellulose units. Weil-marked stages in 
the series occur at the points denoted by the empiri- 
eal formule CyHiO,CSSNa. The former represents an 
equilibrium attained after the solution has remained for 
some hours at the ordinary temperature: the latter is reached 
in from three to four days. The cellulose under the reaction 
acquires a more acid character, an additional OH group 
combining with alkali. The lower terms of the series, 
though insoluble in water or dilute saline solutions, are 
dissolved by the addition of sodium hydrate. The sodium 
atom in combination with the CSS residue is not attacked 
by weak acids, such as acetic acid. By double decomposition 
with soluble salts of Cu, Zn, etc., the corresponding xanthates 
are produced as insoluble colloidal precipitates. 

In the above reactions the cellulose aggregate is main- 
tained ; the solutions of the derivatives are viscous and 
colloidal ; but the following 

Reactions of decomposition, which are determined’ by 
hydrolytic and oxidising agents, the directions of resolution 
are extremely various and the relationships of the products 
to the original aggregate are undetermined. 

(a) SULPHURIC ACID, sp. gr. 1°55—1°65, dissolves the 
cellulose as a disulphuric ester; but decomposition attends 
the reaction, and on diluting and boiling the hydrolysis is 
carried to the extreme molecular limit, the final product 
being dextrose. 

(b) Hypropromic acrp in ethereal solution attacks the 
cellulose profoundly with production of brom-methyl fur- 
fural. The formation of this compound indicates a previous 
or intermediate stage in which the products of resolution 
are molecular ketonic bodies of carbohydrate constitution. 

E 2 


62 WOOD PULRFAND ITs USES 


(c) HyprocHLoric acrp in presence of water, dilute sul- 
phuric acid, and acids generally, attacks the cellulose aggre- 
gate with production of a variety of derivatives. (1) Jn- 
soluble : These are generally termed hydrocelluloses. They 
are disintegrated residues of the original fibres; they differ 
chemically from the parent aggregate in the presence of 
free aldehydic groups, and in readily yielding to the action 
of alkalis. (2) Soluble molecular products, chiefly dextrine 
and dextrose. 

(d) AuKaLIne Hyprates and ALKALIS generally have little 
action on cellulose in the form of dilute solutions—even 
when treated at elevated temperatures. Sodium hydrate in 
solution of concentrations of 12 per cent. NaOH and upwards, 
combines with the cellulose, producing profound structural 
modifications (mercerisation), but without resolving the 
ageregate. 

At higher concentration and temperature the cellulose is 
partially dissolved; but even under the conditions of a 
‘fusion’ at 180° the resolution is limited to the conversion 
into alkali soluble modifications, which are precipitated in 
the colloidal form on diluting and acidifying. At higher 
temperatures (250°) and with larger proportions of the 
alkaline hydrates, the cellulose is resolved into acid products 
of low molecular weight, chiefly acetic acid and oxalic acid. 

Oxidants.—The directions of oxidation of cellulose are 
likewise extremely diversified. The aggregate manifests 
considerable resistance to alkaline oxidants in dilute form, 
e.g., solutions of the hypochlorites, permanganates ; but when 
the limit is passed the oxidations which result are drastic 
in the sense that the soluble products are of low molecular 
weight, chiefly carbonic and oxalic acids. The insoluble 


CELLULOSE AS A CHEMICAL INDIVIDUAL 53 


fibrous residues, more or less disintegrated, are known as 
oxycelluloses. They contain free aldehydic groups, are 
easily attacked by hydrolysing agents, and on boiling with 
hydrochloric acid (1°06 sp. gr.) are decomposed with 
production of some furfural. 

Resolved by the action of concentrated solutions of the 
hypochlorites, cellulose yields chloroform and carbon-tetra- 
chloride. The hypobromites give the corresponding bromine 
derivatives. Nitric acid (1°25 sp. gr.) at 180° converts 
cellulose into a series of ‘‘ oxycelluloses,” which are resolved 
on boiling with calcium hydrate into acid products, among 
which isosaccharinic and dioxybutyric acids have been 
identified. In the original oxidation small quantities of the 
higher dibasic acids—sacchari¢ and tartaric acids—are pro- 
duced, but the main products are oxalic and carbonic acids. 

With chromic acid an endless series of oxidations may be 
effected, the degree of action depending upon the proportion 
of the active oxidant and the associated hydrolytic action of 
mineralacids. The oxycelluloses produced are distinguished 
by relatively large yield of furfural when decomposed by 
boiling HCl Aq (1°06 sp. gr.). In presence of sulphuric 
acid there ensues complete combustion, and the reaction is 
the basis of quantitative analytical methods. 

Resolution by Ferment Actions—Under the actions of 
specific organisms the cellulose complex is totally resolved, 
the main products being methane, hydrogen, and carbonic 
and fatty acids. ‘I'he decomposition may be associated with 
the action of an enzyme; but a remarkable feature of the 
process is the absence of intermediate products, at least in 
the cases hitherto investigated. In the digestive tract of 
the herbivora cellulose is resolved, and from the investiga- 


o4 WOOD PULP AND ITS USES 


tion of the process, necessarily by indirect observations, it 
appears that, in addition to a destructive resolution to 
ultimate gaseous products, there occurs a resolution to 
proximate groups of high nutritive value, which are 
assimilated by the animal organisin. 

Resolution by Heat; Destructive Distillation.—The decom- 
positions of cellulose at temperatures exceeding 250° are 
necessarily extremely complex. 

The groups of products show an average production : 


Solid Liquid Gaseous 
50 per cent. 50 per cent. 20 per cent. 
Charcoal or pseudo- Containing Chiefly 
carbon Acetic acid (2 per cent.) COand CO, 


Methyl spirit (7 per cent.) 
Acetone, furfural 
tar (12 per cent.) 


the actual proportions and composition of these mixtures 
varying with the temperature and duration of the heating. 

General View of the Decomposition of Cellulose.-—It is 
clear that the cellulose complex breaks down under destruc- 
tive influences, in directions depending upon the nature 
of the attacking agent, its concentration, and all the 
surrounding physical conditions. The study of these 
decompositions has thrown but little hght on the actual 
nature and constitution of the cellulose aggregate; for the 
reason, perhaps, that we have endeavoured to maintain a 
basis of interpretation such as is applicable to ordinary 
molecular compounds or complexes. If we regard cellulose 
as the analogue of a complex salt in presence of water, and 
endeavour to follow the reactions of decomposition as we 


CELLULOSE AS A CHEMICAL INDIVIDUAL 55 


should the changing equilibrium of a colloidal salt solution 
under the action of reagents, we have a basis of working 
hypotheses which will be found to stand the general test of 
credibility—that is, they tend to progress in investigation. 
We make this observation in reference to the matter which 
we have just endeavoured to reduce to short, systematic 
expression, but which obviously cannot effectually be so 
treated, because it involves the entire theoretical basis of 
our subject—that is, the actual state of matter and the 
distribution of the reactive unit-groups in the cellulose 
complex; and this basis is as yet entirely undetermined. 
The Cellulose Grouwp.—F rom the typical cellulose we pass 
to the diversified group of celluloses. Their general charac- 
teristics are those of the prototype; the variations they 
present are especially such as involve the undetermined 
factors of constitution. With these there are certain cor- 
relative variations which afford an empirical basis of 
classification. These are (a) the degree of resistance to 
hydrolytic and to oxidising agents, (b) the percentage 
yield of furfural when decomposed by boiling HCl Aq, 
(c) elementary composition, in respect of the ratio C: O. 
The fibrous celluloses are grouped as follows :— 


Cotton Wood cellulose Cereal cellulose 
sub-group A. sub-group B sub-group CO 
Type. Bleached cotton. Jute cellulose. Straw cellulose. 
Elementary j (C) 440—444 438°0—43°5 41°5—42°5 
Composition | (O)  50°0 51:0 53°0 
Furfural . . O1—O04 3°O—6'0 12°0—15°0 
Other character- 
istics. . Noactive Some free Considerable 


CO groups. CO groups. — reactivity of 
CO groups. 


56 WOOD PULP AND ITS USES 


Of these groups the following points may be noted :— 

A.—Comprises, in addition to cotton, other industrially 
important celluloses, ¢.g., flax, hemp, and rhea. They 
occur in the plant world in association with compounds 
easily removed by the action of alkalis. They pass through 
the cycle of reactions involved in their solution as xanthate, 
without hydrolysis to soluble derivatives. 

B.—tThese celluloses are obtained as products of decom- 
position of a compound cellulose. They may be regarded 
as partially hydrated or hydrolysed. ‘They are more 
readily attacked by hydrolysing agents and, in the xanthate 
reactions, are partially resolved to alkali-soluble derivatives. 

C.—These celluloses are in most cases a complex of 
structural elements, and not homogeneous chemically. 
They are still less resistant than the preceding group, and 
more especially the furfural-yielding components, which are 
selectively attacked under certain conditions. 

The cellulose groups, as above, pass by imperceptible 
eradations into a heterogeneous class of natural products 
which, while possessing some of the characteristics of the 
celluloses proper, are so readily resolved by hydrolytic treat- 
ment that they must represent a very different constitutional 
type or types. ‘To this group of complex carbohydrates the 
class-name hemicellulose has been assigned. They are struc- 
turally different from the fibrous celluloses, occurring mostly - 
in the cellular form (parenchyma, etc.). They differ in physio- 
logical function and in being readily resolved by hydrolysis 
into the crystalline monoses. 

IE. 


We have now to deal with the complex of groups in com- 
bination with the cellulose in the ligno-celluloses. They 


CELLULOSE AS A CHEMICAL INDIVIDUAL d7 


are conveniently grouped under the neutral term ‘non- 
cellulose’’; but in view of their leading characteristics, 
which are those of the di-ketones, or more particularly 
quinones, they are more aptly described by the term 
“ lignone.”’ 

A ligno-cellulose as a compound of cellulose and lignone 
is differentiated from cellulose in many important respects. 
First, in elementary composition it presents a striking 
contrast, as will be seen from the subjoined numbers :— 


Cellulose. Typical Ligno-celluloses, 
Jute. Pinewood. Beechwood. 
Carbon . : 44°4 47°0 48:4 49°1 
Hydrogen ; 61 671 6°3 §°2 
Oxygen . 49°5 46°9 45°3 44°7 


Applying a statistical calculation to one of the ligno-cellu- 
loses, we may conclude that the lignone complex is a body 
of much higher carbon contents (57 per cent.) than cellulose 
(44 per cent.). Thus :— 


Carbon. 

i 75 x 44 ae 
Ligno-cellulose Soest 100 goin 
Jute Thos Veen (. 14°25 
8 100 Hene 
47°25 


Further we may calculate from the figures that the ratio of 
the elements in the lignone is approximately C5: H¢: O3 
expressed on a Cg unit. 

T'wo reactions of the lignone are of importance in enabling 
us to fix this empirical formula more closely, as well as 
certain constitutional relationships. 


d8 WOOD PULP AND ITS USES 


Chlorine-—The lignone reacts quantitatively with chlor- 
ine, combining with the halogen, that is, in a characteristic 
and invariable proportion. In the case of jute this propor- 
tion is 8 per cent. of the ligno-cellulose, and an equal 
proportion is converted with hydrochloric acid. In the 
woods, the chlorine combining is higher in proportion 
to the higher percentage of lignone groups; but the 
hydrochloric acid produced is much higher. The chlor- 
inated complex is soluble in certain neutral solvents, such 
as alcohol. The analysis of the chlorinated derivative 
obtained from jute establishes the formula CygHigCliO9, and 
the investigation of the reaction has shown that the ignone 
is integrally attacked. The chlorinated derivative reacts 
with sodium sulphite in aqueous solution, and is converted 
into a soluble sulphonated derivative, being quantitatively 
eliminated from the cellulose. This reaction is employed 
for the quantitative resolution of the ligno-cellulose and the 
estimation of its cellulose contents. The chlorinated group 
in the lignone derivative is identified as a quinone chloride, 
and the complex thereby definitely connected with the 
aromatic or benzene group of carbon compounds. The 
chlorinated group is converted by treatment with nascent 
hydrogen (zine and sulphuric acid) into a derivative of 
pyrogallol; and the complex is thus closely related to 
the ‘‘tannins,” of which the trihydroxybenzenes are as 
characteristic constituent groups. Incidentally it has been | 
shown that the hgnone complex, in further contrast to 
cellulose, contains but a small ‘proportion of free hydroxy 
eroups. 

Bisulphites.—The lignone reacts integrally and selectively 
with the bisulphites of the alkali and alkaline earth metals ; 


CELLULOSE. AS A CHEMICAL INDIVIDUAL 59 


a ligno-cellulose treated with solutions of these compounds 
at elevated temperatures and under pressure is quantita- 
tively resolved into cellulose obtained as an insoluble residue 
of the ultimate fibres, and soluble sulphonated derivatives 
of the lignone. This process is not only quantitative, but 
fulfils the further requirements of an economical industrial 
process, and it is therefore extensively employed in the 
preparation of wood cellulose or wood pulp from the woods 
of the conifer. As an industrial process it will be fully 
described in a subsequent chapter. At this point we are 
concerned with the nature and composition of the soluble 
by-products, which are, in effect, the lhgnones in combina- 
tion with the bisulphite residues. ‘lhese compounds have 
been separated in various derivative forms and analysed, and 
the following empirical formule have been established :— 
(Cellulose, pp. 200, 201). 
From analyses of product precipitated by hydrochloric 

acid 

CosHo4(CH3)25 019. 
From analyses of compounds obtained by precipitation with 
lead oxide 

CosHos(CH3)250 10. 
Brominated derivative 

Co4Ho2(C Hs)oBrySOu. 

The parent molecule or lignone complex of the wood may 
be taken to have the composition | 

Cos Ho1(C Hs) 2010. 


The above reactions of the lignone complex are specially 
characteristic; they are simple and quantitative, and as 
they are devoid of secondary complications, the derivatives 
are in simple relationship to the parent complex. But the 


60 WOOD PULP AND ITS USES 


more complete characterisation of the lignone is necessarily 
based upon the study of reactions of decomposition. 

These are, however, extraordinarily complex, and in 
accordance with our present treatment of the subject, our 
description will be limited to a general outline. 

Chromic Acid in presence of a hydrolysing acid attacks 
the lignone complex in the cold. The reaction has been 
specially studied in the case of jute. The important 
features of the decomposition is the complete breakdown to 
acid products of the lowest molecular weight—carbonie, 
formic, acetic and oxalic acids. ‘This bears a direct 
interpretation in reference to the constitution of lignone ; 
it excludes hydrocarbon nuclei of any but the smallest 
dimensions, notwithstanding the large dimensions of the 
lignone formula; and further implies a relatively high 
proportion of CO groups, alternating in periods of short 
dimensions with hydrocarbon groups. When the reaction 
is apphed to the lgno-cellulose the action is confined to 
the lignone, so far as 1t may be described as a destructive 
oxidation, but extends to the cellulose in converting it into 
an ‘‘ oxycellulose ’’ largely soluble in alkaline solutions. 

Nitric Acid attacks the ligno-celluloses at all concentra- 
tions and temperatures, and under most conditions effects a 
destructive resolution of the lignone. The following are 
the results of a statistical investigation of the decomposition 
of jute ligno-cellulose :— 


Ligno-cellulose and Nitric Acid (10% HNOs) at 60—80°, 
Cellulose a. Oxalic acid. Complex unstable acid. 


Solid products 2 .68=—06% 40—55% 
Volatile products . Acetic and Formic acids (14—18%) 
Gaseous products . From HNO, From Ligno-cellulose 


N20,4,N202,N20,No, HCN CO,—CO—HCN 


CELLULOSE AS A CHEMICAL INDIVIDUAL 61 


Cellulose a is a more stable and resistant cellulose 
by contrast with cellulose 6 which is attacked under 
the above conditions, though resistant to chlorine, and 
therefore to the conditions of the process described on 
Doo. 

This reaction has been the subject of various patents and 
attempts to develop upon it an industrial process for the 
preparation of cellulose. 

As regards the theoretical bearings of these results, the 
far-reaching resolution of the lignone under an attack 
which cannot be described otherwise than as of very 
moderate intensity, further confirms the conclusions as to 
the prevalence of CO groups in the lgnone complex, 
alternating with hydrocarbon groups of relatively small 
dimensions. Of other acid resolutions we shall mention as 
yielding characteristic products : 

Hydrochloric Acid.—The aqueous acid at a concentration 
of 12 per cent. HCl (sp. gr. 1°06) determines a highly 
complex series of changes at the boiling point. Both the 
cellulose and lignone are profoundly attacked. The 
characteristic product is the volatile aldehydic substance 
furfural, which distils, and may be quantitatively estimated 
in the distillate. The yields of this aldehyde are charac- 
teristic of the various types of ligno-celluloses :— 


Average yields of furfural /Jute . 8°0 
from typical ligno- Beechwood . : eee List) 
celluloses. { - purif. Alkalis 12°0 

Coniferous woods . 4°0—5°0. 


It may be noted that the furfural-yielding constituents 


62 WOOD PULP AND ITS USES 


of the ligno-cellulose occupy an intermediate position in 
function and relation between the lgnone and cellulose. 
Thus in isolating the cellulose by the chlorination process, 
a cellulose is obtained which yields 6—8 per cent. furfural 
on boiling with the acid; this cellulose is the § cellulose 
mentioned on p. 61. Further, on treating the lgno- 
celluloses with alkaline hydrates in the cold, a constituent 
is dissolved, which is separated on acidifying the solution, 
as an amorphous colloidal precipitate. Beechwood yields 
this product in exceptional proportion. It is known as 
wood gum. It is characterised by its high yield of furfural, 
viz., 8383—48 per cent. according to its degree of “ purity,” 
i.e., the freedom from associated groups of the characteristic 
an anhydride 


’ 


component. This body is a ‘‘ Pentosan,’ 
of the C; sugars, an analogue of starch, which may be 
regarded as an anhydride of the Cg sugar dextrose. These 
C; sugars do not occur free in the plant world; but in the 
form of these amorphous and colloidal anhydrides are very 
widely distributed as constituents of plant tissues. The 
condensation to furfural as a main reaction, though 
characteristic of these C; sugars, is not an exclusive 
constitutional index, and there are many possible group- 
ings which might undergo this condensation. It is there- 
fore usual to adopt the more general term of furfuroid 
in describing such plant or constituents as yield furfural; 
the narrower identification as a pentosan depends upon 
the actual production of the C; sugars as products of 
hydrolysis. 

Alkaline Decompositions.—The lignone group is attacked 
by alkaline solutions at elevated temperatures and converted 
into soluble derivatives, which are acid in character, but 


CELLULOSE AS A CHEMICAL INDIVIDUAL 63 


for the most part of ill-defined constitution. The cellulose, 
resisting the action of these reagents, is separated and is 
obtained as a disintegrated mass of fibrous or cellular 
units, constituting a “pulp.” Upon these decompositions 
are based an important group of industrial processes for 
the preparation of wood pulps, which will be found 
described. 

Having by this discussion obtained a general knowledge 
of the ligno-celluloses as chemical compounds, and also of 
the ultimate component groups of both lignone and cellulose, 
we are in a better position to deal with certain special 
properties and reactions of the ligno-celluloses, either 
involved in the industrial applications of those products 
which they to some extent define and limit, or employed in 
their quantitative estimation when present as constituents 
of a fibrous mixture. 

Some of the characteristic reactions of the ligno-celluloses, 
about to be described, appear to be due to actual furfural 
derivatives present in the complex. The pentosans, on the 
other hand, if assumed to be the mother substance of the 
furfural obtained, are saturated derivatives, and their 
composition and properties are such as would leave many 
of the characteristics of the lignone complex unaccounted 
for. 

Hydriodic Acid decomposes the ligno-celluloses with 
liberation of methyl iodide, and the production and estima- 
tion of this volatile product, is taken as the index and 
quantitative measure of methoxyl OCH; groups present in 
the ligno-cellulose. This ethereal group is a further 
‘chemical constant of lignification.” ‘The percentages of 
ethereal methyl groups are remarkably uniform for a very 


64 WOOD PULP AND ITS USES 


large range of woods or ligno-celluloses. The following 
have been determined (Cellulose, p. 189) :— 


A. Woops. 
CH3 p.ct. 
Maple . Stem ; : : . Acer Pseudo-platanus, L.. 3:06 
4 » extracted! : : me " ‘Wen BO 
- : ,, Shavings . z : én " OO 
Acacia . Branch . ; . . Robunia Pseud-Acacia, Li. 2°37 
a . Extracted : . - - . 245 
Birch . 8 years old : : . Betula alba : ; 2 pao 
Pear . . Stem : , : . Pyrus communis, L. . > Sw 
Oak . : e E : , . Quercus pedunculatus . 2.86 
yt oe - $5 : : * . 4 Saito 
Alder . : 3 ; ; . Alnus glutinosa ‘ Paro 
Ash . . Stem : ; ; . Fraxinus excelsior, L. eRe 
Fi : . Shavings from stem. F 3 :, . 269 
5 5; . Stem shavings extracted . 7 260 
7 : . Shavings from branches . 5 7 oO Ue 
. (Shavings from branches ) 2-91 
ae iy . | extracted . : 3) 2 i 
Jivee 02 . Stem : : : . Abtesexcelsa . d . 215 
” ° : ” . 2 “ é ” x : 2°25 
7 As . 5 : % : 2°39 
_ ,, (central zone) . ‘ iy ip ‘ ; . .2'59 
MS 5, (sap wood) A ; $ or : : . 2:32 
he eC ; ; : } . Abies pectinata, DC. . 2:45 
Pine . : : F ; : . Pinus sylvestris, L. . . 2°25 
ms Stem ; i . . Pinus laricis . ; ve? OS 
ide, : 5 : : , : Hf ; ; : ae 
Cherry - : ; : . Prunus Avium, L. . hee” ests) 
Larch : tf ; : : . Larix europea, DC. . . 199° 
Sete ibis: ; 4 ; ; : F 7 fe : 2°68 
Lime . : ~ : ; . Tilia parvifolia ; Pair) 3) 
Mahogany . . : ‘ 4 . Swietenia Mahagom, L. . 2:66 
Walnut. hs i j : . duglans regia, L. : Nee ey 
pea es . Shavings from stem : 3 7 : Eso 
Poplar . Stem : : ; . Populus alba. ; Sees) 
Beech : i : : : . Fagus sylvatica Eom 
ff Vez ; 4 ; : ; ; a a ‘ eer Oe 
MLA 5 » shavings . : ‘ re i; : acta 


1“ Hxtracted” signifies previously exhausted with water, alcohol, 
and ether. Otherwise the specimens were analysed without previous 


preparation. 


CELLULOSE AS A CHEMICAL INDIVIDUAL 65 


CHs p.ct. 
Klm . . Stem . i : . Ulmus campestris pe ate: 
:. : : ,, Shavings extracted . . mp i Ae Dia gs) 
Willow : : P : , . Salia alba ‘ : ae ol 
B. Frsrous Propucts.—Natural and prepared. 
Jute (Lignocellulose) . : : : : : ; f : me Sei 
Swedish filter paper : : : A ; ‘ : . m0 
Cotton p ‘ : : : ‘ ; ; ‘ ; ; = 0:0 
Flax, unbleached . : ; : . Linwn usitatissimum 7 00 
Hemp e F : : : . Cannabis sativa ; 3 0°29 
China Grass, unbleached , ; . Béohmeria nivea ; ep Oy 
Sulphite (Cellulose) : : . Pinus sylvestris ‘ . 0:34 
C. MISCELLANEOUS. 
Cork : , ; ; : : . Quercus suber . : . 2°40 
; : : : : : : 3 y : Ay 
Nutshells : : : . duglans regia . : . 374 
Lignite (Wolfsberg) : : ; ‘ : : . 244 
Brown coal 0:27 


In reference to actual molecular proportions it is to be 
noted that in the sulphonated derivatives obtained from 
the lignones of coniferous woods the proportion is indicated 
by the formula CyHo(CHs)250O1. The localisations of 
these methyl groups is a present object of investigations ; 
and their presence is established in the celluloses isolated 
from the ligno-celluloses. Thisis taken as an indication of 
a genetic relationship between cellulose and lignone. 

We may now set out the main features of the chemistry 
of the igno-celluloses in a brief *éswmé as follows :— 

With the typical characteristics of the celluloses as 
complex aggregates, the ligno-celluloses similarly react 
with the zine chloride reagents to form colloidal solutions ; 
also to form esters with nitric acid, acetic anhydride 
and benzoyl chloride, respectively nitrates, acetates, and 


Wake, F 


66 WOOD PULP AND ITS USES 


benzoates. But such reactions are in the main those of 
the cellulose constituents of the complex, the latter remain- — 
ing unresolved. The lignone groups with which the 
cellulose is combined or associated are sharply differen- 
tiated from the cellulose not only by higher carbon per- 
centage and low molecular proportion of OH groups, but 
by constitution; they are unsaturated, cyclic compounds, 
and hence react synthetically with chlorine, bisulphites 
and nitric oxides. 

They are greedy of oxygen, and are profoundly attacked by 
all oxidising agents, are even subject to progressive attack 
by atmospheric oxygen. Hence the ligno-celluloses as con- 
stituents of papers lower the qualities of these important 
industrial products, not only from their inferior intrinsic 
paper-making quality, but from the changes which take 
place as a result of atmospheric oxidation: these are, 
discoloration and loss of tenacity. Cellulose, as a satu- 
rated compound, is free from this cardinal defect, and we 
have practical evidence of this in the extraordinary 
resistance to atmospheric influences of papers and textiles 
which have been preserved to us from the Middle and 
earlier ages. 

Associated with these constitutional features we have a 
well marked and diversified dyeing capacity : the ligno- 
celluloses are dyed easily and by colouring matters of 
widely varying constitution, whereas the celluloses proper 
have a selective or limited tinctorial capacity. 

As regards intrinsic “‘ colour,” the ligno-celluloses occur 
in forms which would be described as grey, yellow or brown 
—but such colours are mostly due to associated by-products. 

When freed from these by certain standard methods of — 


CELLULOSE AS A CHEMICAL INDIVIDUAL 67 


“bleaching” they assume a bright cream to whitish 
colour. But bleaching processes are based upon alkaline 
and oxidising treatments, to both of which the lignone con- 
stituents are extremely sensitive. Hence the limitations of 
ligno-cellulose textiles, such as jute, in respect of colour. 
The substance will not sufficiently resist the necessary treat- 
ments for a “high bleach.”’ Another feature of inferiority 
is a joint product of the relative shortness of the ultimate 
fibre and want of resistance to the chemical actions of 
hydrolysis and oxidation. From a practical point of view 
the ligno-celluloses are composed of cellulose units of short 
dimensions (1—3 mm.) cemented together by the lignone 
components. When these are removed the fibre is disin- 
tegrated ; for itis evident that structural units of }in. length 
cannot cohere, and the strength of a yarn or fabric pre- 
senting this condition can only be that due to the adhesion 
of the fibres, as in a sheet of paper. When wetted the 
adhesion is reduced to a fractional proportion. Hence the 
bleaching of ligno-celluloses is a matter of practical com- 
promise, and a ligno-cellulose fabric, bleached or unbleached, 
is always tending, however slowly, to disintegration, as 
a result of the attack of the natural and all-pervading 
agencies oxygen and water. 

It is necessary for a thorough grasp of the chemical 
technology of the woods, to take the logical road of 
studying the jute fibre as a structural type, and the jute 
fibre-substance as a typical ligno-cellulose. From the 
latter point of view it occupies the mean position between 
the celluloses and the perennial woods, and it will be 
found to be generally true of the characteristic reactions 
of these substances. Thus jute is attacked by the 

F 2 


68 WOOD PULP AND ITS USES 


cuprammonium reagent and for the most part dissolved ; 
but the ligno-celluloses of the woods are scarcely affected. 
Strong solutions of the caustic alkalis produce the effects 
of ‘‘ mercerisation ”’ upon jute and fibrous ligno-celluloses of 
similar composition, but not upon the woods. Moreover, 
if mercerised jute, retaining the soda (NaOH) be exposed 
to carbon bisulphide, synthesis of a xanthogenic acid 
occurs, as with the celluloses. But the reaction is compli- 
cated by the presence of the lignone groups, and the 
product, instead of -being entirely soluble to a structureless 
solution, is swollen or distended by water to practically 
indefinite limits, and after being so distended, if then 
decomposed it reverts to a fibrous mass. In the case of 
the woods, on the other hand, there is no perceptible 
attack even on prolonged joint action of the alkali and 
carbon bisulphide. The higher proportion of lignone con- 
stituents in the woods, with decreased percentage of 
cellulose, has the effect, therefore, of producing a condition 
of resistance to reaction, or chemical inertness. Doubtless 
this is related to the physiological functions of the woods 
and their persistence during the prolonged period of life 
of trees; and this property of inertness is attained by 
increase in groups which are highly reactive and extra- 
ordinarily “ labile.’ The result appears to be paradoxical, 
and involves a natural equilibrium of obviously profound 
significance. 

This will be more fully appreciated from a consideration 
of certain characteristic colour reactions of the ligno- 
celluloses, which are a certain measure of, being quantita- 
tively related to, their lignone constituents. 

Ferric Ferricyande.— The red solution which results 


CELLULOSE AS A CHEMICAL INDIVIDUAL 69 


from the interaction of ferric salts and alkaline ferri- 
cyanides in solution thus :— 


FeCls + K3FeCys = 3 KCl + FeCy, 


colours the lgno-celluloses a deep blue as a result of 
deoxidation of the ferric compound and reduction to the 
complex cyanides known as Prussian blue, Turnbull’s 
blue, etc. These separating as colloidal hydrates are 
deposited in a state of intimate union with the ligno- 
cellulose substance, and in the case of the jute fibre it is 
easy to see by microscopic examination that the colloidal 
blue pigment is structurally incorporated with the fibre 
substance. The amount so combining may be 380—40 per 
cent. of its weight, without changing the external character- 
istics of the fibre, z.e., form and lustre. The reaction is of 
use in following the progressive elimination of the lignone 
constituents in the processes of isolating cellulose. 

Students who wish to follow up this interesting reaction 
are referred to Journ. Soc. Chem. Ind. 

Phenols. — The aldehydic and ketonic constitution of 
the ligno-celluloses determines characteristic reactions with 
aromatic hydroxy derivatives or phenols. One of these is 
exceptionally striking. 

Phloroglucol, the symmetrical trihydroxybenzene (C¢Hs . 
O'H . O°H . 0’H) in solution in aqueous hydrochloric acid of 
1:06 sp. gr. reacts with production of coloured derivatives of 
magenta-red hue. 

The depth of colour developed is constant for any given 
ligno-cellulose, and may be used asa quantitative estimation 
of ligno-celluloses in intimate admixture with non-reactive 
substances such as cellulose. 


70 WOOD PULP AND ITS USES 


Ordinary printing papers are a mixture of ‘ ground 
wood’’ pulp, and ‘“‘ chemical” pulp or cellulose, and the 
depth of coloration obtained in moistening with the 
‘“‘ phloroglucol reagent” affords an approximate measure of 
the proportion of the former or ligno-cellulose. 

A closer study of the reaction has shown that it consists 
of two phases; the coloured bodies result from a minor 
reaction reaching a maximum with less than 1 per cent. 
of the phenol per 100 parts of the ligno-cellulose: the 
major reaction takes place without development of colour 
and ‘‘ fixes’’ a further 6—7 per cent. of the phenol in com- 
bination as a productof condensation. The colour-reactions 
appear to be due to aldehydes of the furfural type, probably 
hydroxy furfurals. 

As a result of this further investigation a more strictly 
quantitative method has been devised which measures the 
total phenol combining, and by calculation the proportion of 
ligno-cellulose in mixtures. (See Ber. Deuts. Chem. Ges., 
40, 3119, 1907.) 

Aromatic Bases, such as aniline and substituted anilines 
react with constituent groups of the ligno-cellulose complex, 
giving characteristic yellow to orange colorations. 

With dimethylparaphenylenediamine the reaction 1s 
more striking, the colour developed being a ‘“ magenta”’ 
red. With the ligno-celluloses in their normal state the 
colorations are constant, and are therefore an approximate 
quantitative measure of the proportion of ligno-cellulose in 
admixture with non-reacting substances such as cellulose. 
The method devised by Wurster consists in developing the 
colour reaction and comparing the depth of colour with a 
eraduated scale of fixed tints. 


CELLULOSE AS A CHEMICAL INDIVIDUAL 71 


It is to be noted again that these reactions are not 
characteristic of the ligno-cellulose as such. They are 
weakened by treatment of the ligno-celluloses with reagents 
of feeble intensity, such as sulphurous acid and sulphites 
under conditions which leave the lgno-cellulose itself 
unaffected. They are reactions, as in the case of the 
phenols, with by-product groups, invariably present. 
There is evidence that these groups are the same as those 
which react with the phenols. (See also Ber. Deuts. Chem. 
Ges., 40, 3119.) 


Tigno-cellulose and Photo-chemical Phenomena. 


We cannot close this theoretical account of the lgno- 
celluloses without introducing the researches of the late 
W. J. Russell on “ The Action of Wood on Photographic 
Plates in the Dark” (Phil. Trans. B., 197, 281, 1904; also 
Lec)... 10, 000 > 90; 376). 

We are indebted to Mr. W. F. Bloch, who assisted 
Dr. Russell in these investigations, for the following notes 
of their results :-— 

Russell found that all the woods were able to give definite 
pictures upon a photographic plate, in absence of light. 

The action takes place when the wood is kept at a 
considerable distance from the plate; but for perfect 
definition, contact was necessary. The pictures usually 
corresponded with the visible structure of the wood ; but in 
some cases there was a marked differentiation. 

This selective activity appeared to depend in part upon the 
resinous constituents of the wood and its disposition on the 
cells; but also in part upon the nature of the cell-wall 


72 WOOD PULP AND ITS USES 


structure itself, which in cases offered much resistance to 
the passage of the active bodies. 

On the evidence the active bodies must be regarded as 
an emanation, but differing entirely from  radio-active 
emanations. . 

All the properties ascertained identify the substance with 
hydrogen peroxide. 

Ordinary photographic dry-plates may be used to produce 
this effect ; care must be taken to select such as have been 
preserved in wrapping materials themselves unable to act 
upon the plates. | 

The action takes place slowly at ordinary temperatures 
(one day to twenty-one days) according to the nature of the 
specimen, but rapidly at 50—55° C. (half to’ eighteen 
hours). 

The shorter exposures give sharper pictures, which 
observation accords with the conclusion that the active 
body is of the nature of a vapour or volatile compound. 

Bark and pith structure are almost inactive. Within the 
bark there is a bark-forming tissue, which gives alternate 
layers of active and inactive tissue. The latter was also 
found to have the property of being impervious to hydrogen 
peroxide. 

The activity of the woods is increased in all cases by 
exposure to strong light, and observations on the spectrum 
showed that the blue end was particularly active. 

The increased activity disappears on keeping the speci- 
mens after exposure in the dark. 

Resinous substances extracted from a number of woods 
were found to be all more or less active. Para-abietic acid 
was prepared and found to be particularly active. It is 


Action , 


of wood on 


photographic plate in the dark (W. J. Russell, 
Phil. Trans. B. 197—281),. : 


Fig. 138.—Oak. 


Fig. 134.—Larch. 


"ITT YOIOON—'aeT “O17 ‘gonidg—‘oe] “OI 


VY 


CELLULOSE AS A CHEMICAL INDIVIDUAL 76 


well known that this body shows the phenomenon of aut- 
oxidation, which is no doubt associated with its unsaturated 
constitution. 

The fossil resins show slight activity; coal also shows 
activity, and attempts were made to apply this to the 
identification of different types of coal. 

Woods were exhaustively treated with resin solvents, but 
were found to be still active, and the evidence goes to show 
that we are dealing with a definite property of the ligno- 
celluloses. 

It is to be noted that a short exposure to steam or to 
chlorine gas renders the wood substance inactive. 

The action is arrested in an atmosphere of carbonic gas, 
but is stimulated by the presence of oxygen. 

Experiments in which the active substance in sufficient 
mass was swept witha stream of air, and the current of air 
afterwards made to act upon a photographic plate at some 
distance, showed that the active substance could be carried 
forward. | 

It was also found that diaphragms carrying any substance 
capable of absorbing and destroying hydrogen peroxide 
arrested the action. 

The investigation is stillat this empirical stage. Russell 
has left an interesting legacy of highly suggestive observa- 
tions, and the matter invites further investigation, as the 
exploration of the causes is calculated to throw a very 
important light on the natural chemical equilibrium of the 
higno-celluloses. 


CHAPTER III 


WOOD PULPS IN RELATION TO SOURCES OF SUPPLY: FOREST 


TREES AND FORESTRY 


THE use of wood pulp as a raw material for the manu- 
facture of paper is of comparatively recent origin, its 
commercial application for this purpose dating from 1869, 
when about 60 tons of mechanical-ground wood pulp 
were exported from Norway to Engiand. In the following 
year the quantity rose to 500 tons, and from that year 
onward the industry has grown by leaps and bounds, the 
total amount of wood pulp imported in 1909 being over 
500,000 tons. 

At the present rate of consumption of wood. for paper- 
making, the devastation of forest areas has become so 
serious a matter that the Governments of the various 
countries in which these forests exist are taking vigorous 
steps in the first instance to prevent their absolute destruc- 
tion, but further to secure a systematic upkeep. 

It is very difficult to arrive at accurate figures repre- 
senting the world’s production of wood pulp; but from the 
sem1-official published returns an approximate estimate may 
be obtained. In dealing with these returns it is to be noted 
that the systems of measurement, the methods of recording 
results, and the tabulation of the records are different in 


~I 
=I 


SOURCES OF SUPPLY 


each country, and such figures are of little service unless 
reduced to some common standard of measurement. 


TABEES 


SHOWING ANNUAL PRODUCTION OF Woop PULP FOR VARIOUS 
COUNTRIES, CALCULATED ON THE AIR Dry Basis (1907—1908). 


Country. Be dep tae oh. eatedey tan ae ee oot 
Germany . : 315,000 320,000 635,000 
Norway . : 421,000 270,000 691,000 
Sweden . 78,000 510,000 388,000 
Finland . : 69,000 32,000 121,000 
America . : 868,000 988,000 1,856,000 
Canada. ; 565,000 172,000 737,000 

2,316,000 2,312,000 4,628,000 


The most convenient unit which may be taken as the 
basis of measurement for comparison is the “ cord”’ of wood, 
consisting of a number of short logs, each 4 feet long, piled 
up in a space 8 feet long and 4 feet high. Such a pile of 
logs measuring 8 feet x 4 feet x 4 feet = 128 cubic feet, 
is called a “cord” of wood. The unit of weight may be 
taken in terms of the English ton of 2,240 lbs. (See 
p- 85.) 

These figures do not convey even in such concrete 


1 The sources of information from which Table I. has been com- 
piled are as follows:—Germany: Figures given by Dr. Kirchner in 
‘* Wochenblatt,” 1907. Scandinavia: Report British Wood Pulp 
Association, 1909. America: ‘‘ Wood Used for Pulp,” U.S.A. Bulletin. 
Canada: ‘‘ Wood Pulp in Canada,” official report, Geo. Johnston. 
Finland: Paper T'rade Review, 1908. 


rs 


a 


78 WOOD PULP AND ITS USES 


form any accurate picture of the extensive cutting opera- 
tions which are going on, for the manufacture of wood pulp. 
Some idea may possibly be obtained by attempting to 
estimate the number of standing trees felled to supply the 
quantity of pulp wood mentioned. ‘This will vary in 
different countries according to the nature and size of the 
trees. According to general practice, the large trees are 
reserved for lumber and the manufacture of boards for 
building purposes, so that the trees used for pulp may be 
taken at an average diameter of about 9 inches. 

The ordinary spruce or pine tree of this diameter will 
yield three logs, each 16 feet long, and when the logs are 
cut into 4-feet lengths, twelve pieces. 

The number of pieces required to give a piled cord of 
128 cubic feet capacity is about sixty, so that for each cord 
five trees would be necessary. 

Assuming that 1 ton of dry chemical pulp is obtained 
from 2+ cords of wood, and 1 ton of mechanical pulp from 
14 cords of wood, then the total quantity of timber to be 
cut for the production of the amount of wood pulp shown 
in Table I. would be about eight million cords. 

A certain proportion of the trees cut are faulty and 
decayed, while some are lost in transit from the forest to 
the pulp mill, so that the actual number felled for pulp 
wood is somewhat in excess of the quantity indicated. In 
relation to forestry and the destruction of forests, we have 
to consider, in addition to the wood cut for pulp, the number 
of trees required for timber, and the sum of these figures 
reaches formidable dimensions. 

Forestry.—The available forest areas of different countries 
have been given by Schlich as follows :— 


SOURCES OF SUPPLY 79 


TA Bie Lik 
Country. Acres (millions). 
Canada . ; : : ’ : 4 800 
America . : : : 400 
Russia . y : : q . : 500 
Austria-Hungary . ; 46 
Germany . : ; ; 35 
Sweden . , : ; 49 
Spain . : , 21 
Norway . : ify) 
France .. ; 3 : 23 
Italy ; 10 
Roumania ; : : , 5 
Great Britain . ; : : ; a 


The preservation of the forests in wood-producing 
countries is thus an acute problem, and of recent years the 
subject of afforestation has aroused considerable interest 
in England, especially in regard to the industrial possi- 
bilities ; but incidentally also as affecting rainfall, and 
therefore general agriculture. One of the most important 
questions, therefore, in this connection is the calculation of 
area necessary to supply a mill continously with wood 
pulp. 

For example, What area of land planted with spruce and 
hard woods would be necessary to supply a mill having an 
output of 800 tons of newspaper per week ? 

This quantity of paper would require 200 tons of mechani- 
cal pulp and 100 tons of sulphite pulp per week, amounting 
to an annual supply on a basis of fifty weeks’ work, of 
10,000 tons mechanical pulp and 5,000 tons sulphite pulp. 


80 WOOD PULP AND ITS USES 


Taking 1} cords of wood as the quantity required for 1 ton 
of mechanical pulp and 2} cords of wood for 1 ton dry 
sulphite pulp, the annual supply of wood necessary is 
12,500 cords for mechanical, and 11,250 cords for sulphite 
pulp, or an approximate total of 25,000 cords. 

The actual amount of spruce or pulp-producing woods 
per acre varies enormously in different countries and in 
different localities, and it is difficult to fix an average. In 
thickly wooded areas which have not been cut over, the 
quantity frequently reaches 40 to 50 cords per acre; but on 
timber lands which have been continuously “ operated” the 
amount may not exceed 8 to 4 cords. 

Taking 10 cords to the acre as a moderate and probable 
allowance, then in the above case 2,500 acres would be 
required to give the wood pulp necessary for one year. If 
the total forest area was 100,000 acres, then the timber 
available would be sufficient for forty years’ supply. During 
that period the spruce largely reproduces itself, so that by 
progressive and careful management of the forest in the 
matter of planting and reproduction, an area of 100,000 
acres should afford a perpetual supply to the mill quoted. 

Mr. Parker Smith, in a paper entitled ‘“ Afforestation,” 
read before the English Paper Makers’ Association, 1910, 
says that at the Canadian Convention one manufacturer 
stated he could run his mill perpetually on a grant of 
25,000 acres, which would permit of his cutting on a forty 
years’ rotation, and yield, on a basis of 10 tons of pulp per 
acre, a total of 6,000 tons annually. 

Comparing this statement with the one already quoted, 
and assuming that the 6,000 tons consisted of 4,000 tons 
mechanical pulp and 2,000 tons sulphite pulp, the weekly 


SOURCES OF SUPPLY 81 


production of the mill works out at 120 tons of paper per 
week, requiring 10,000 cords of pulp wood. On this com- 
putation the manufacturer referred to was calculating the 
quantity of pulp wood per acre to be 16 cords. 

Pinchot, the well-known American forestry expert, has 
carried out some valuable and elaborate experiments on the 
subject of the growth of spruce. A large area of forest land 
was carefully examined for the nature of the timber, its 
condition, growth, and other important information. 
Careful attention was given to the rate of the growth of the 
timber both in the virgin forest and also on areas which 
had been previously ‘‘operated” for timber. The data 
obtained in this investigation enabled Mr. Pinchot to con- 
struct tables showing the amount of timber which could be 
cut from the forest, and the number of years which would 
elapse before an equal quantity of timber could be cut 
from the same area. One example of this will be 
sufficient :— 

A man owns 100,000 acres, yielding on an average 7 
cords per acre of spruce 10 inches and over in diameter. 
How much can he cut annually if he wishes to obtain 
a sustained annual yield, and how soon can he return 
to the portion cut over the first year, and cut the same 
amount of timber about the same diameter limit as at 
first ? 

In the tables published by Mr. Pinchot the total amount 
of wood with a diameter limit of 10 inches appears to be 
100,000 x 7 cords = 700,000 cords, while the same yield 
of pulp wood could be obtained after thirty-seven years. 
The area to be operated annually will be 100,000 ~ 37, 
namely, 2,700 acres. ‘The annual cut of wood will be 

W.P. G 


82 WOOD PULP AND ITS USES 


700,000 — 87 = 19,000 cords. This illustration, taken at 
random from the experiments of Mr. Pinchot, coincides 
closely with the other cases quoted, and if the diameter 
limit was reduced to 9 inches a larger annual cut would 
have been obtained. 

The problem of forestry has been studied and worked 
out on a successful commercial basis in several Huropean 
countries. In Saxony, for example, the State control of an 
area of 480,000 acres has resulted in a large and profitable 
turnover, giving a steady revenue of increasing amount, as 
well as constant employment to skilled labour. In fifty 
years the State has realised the sum of £40,000,000, and 
the careful scientific methods of cutting, aided by proper 
attention to means for reproduction, has improved the 
quantity and quality of available timber, At a recent 
meeting of the Canadian Forestry Convention it was shown 
that the amount of standing timber in the State of Saxony 
had increased by 16 per cent., even during the period of 
constant cutting, and that the net revenue was 22s. as 
compared with 4s. fifty years previously. 

The same satisfactory results are shown by other’ 
countries in which forestry as a commercial undertaking 
has been treated seriously. 

In England the matter has been under consideration 
for some time, and the Report of the Committee on Re- 
afforestation, issued in 1909, is full of useful and 
suggestive evidence. It is interesting to note that the 
waterworks committees of several large municipal corpora- 
tions, such as Liverpool, Manchester and Birmingham, 
have taken up the question, primarily for the purpose of 
conserving the rainfall incidental to the watershed under 


SOURCES OF SUPPLY ° 83 


control, and then turning the large areas thus acquired 
for maintaining the water supply to useful account by 
planting trees. 

The attractiveness of afforestation in the United Kingdom 
is clearly shown by the Committee’s report. The con- 
clusions arrived at are briefly— 

1. Afforestation is a practicable scheme, the available 
area in the United Kingdom being 9,000,000 acres. 

2. The best rotation to secure a continuous yield of wood 
requires 150,000 acres to be dealt with annually. 

3. Afforestation is a productive investment for the 
development of the full scheme, for 9,000,000 acres 
would require an annual sum of £2,000,000. The net 
deficit would be £90,000 in the first year, rising pro- 
gressively to £38,131,250 in the fortieth year, in which 
period the forest becomes more than self-supporting. 

4. After eighty years the net revenue at present prices 
for timber should be £17,500,000. This represents 3% per 
cent. on the net cost calculated at accumulating compound 
interest at 3 per cent. 

5. Afforestation creates a new industry which does not 
compete with private enterprise, and would afford permanent 
employment to one man per hundred acres, and temporary 
employment to a large number of men during the winter 
months. 

Cost of Afforestation.—The Committee gives the following 
example :— 

We assume, as regards expenses, that :— 

1. 150,000 acres are annually afforested for sixty years, 
and that the cost of the freehold and expenses of afforesta- 


tion amount to £13 6s. 8d. per acre. 
G 2 


84 WOOD PULP AND ITS USES 


2. The annual outlay for administrative expenses is 4s. 
per acre. 

8. One-third of the area is worked on a forty years’ 
rotation, and two-thirds on an eighty years’ rotation. 

4. The cost of re-afforestation is £6 10s. per acre; and 

5. The rate of interest is 8 per cent. per annum. 

We further assume, as regards receipts, that— 

1. Thinnings take place at the end of the twentieth year, 
and at the end of each successive decade from the date of 
planting. 

2. The net receipts for the initial thinnings amount to 
2s. 6d. per acre, and for the succeeding thinnings are at 
the rate of £3, £6, £9, £12, and £15 per acre respectively. 

8. The area which is afforested on an eighty years’ 
rotation yields £175 per acre on being clear-felled at the 
end of eighty years. 

4. The area which is afforested on a forty years’ rotation 
yields £60 per acre on being clear-felled at the end of forty 
years ; and 

5. The rate of interest is 8 per cent. per annum. 

The annual deficit on the transaction rises from £90,000 
in the first to £3,131,250 in the fortieth year; in the 
forty-first and up to the sixtieth year the forest becomes 
practically self-supporting ; in the sixty-first year, and sub- 
sequently, an increased revenue is received, but it is not 
until the eighty-first year that the full results are obtained ; 
in this year and subsequently an approximate equalised 
revenue of £17,411,000 per annum being realised. Further’ 
calculations show that the value of the property would then. 
be £562,075,000, or £106,9983,000 over and above the cost 
of its creation. The equalised annual revenue of £17,411,000 


SOURCES OF SUPPLY 85 


represents a yield of £3 16s. 6d. (approximately) per cent. 
on the excess of accumulated charges over receipts. 


Measurement of Pulp Wood.—The systems for measuring 
wood used in the manufacture of pulp differ in the several 
countries. 


Scandinavia.—The wood is measured in terms of fathoms 
or of cubic metres, the price paid for raw material being 
determined by reference to a table showing the sum to be 
paid for logs of varying lengths and varying diameters. 


One fathom = a Toot, 
One cubic fathom = 216 cubic feet. 


Germany.—Wood is usually measured in Germany and 
other Continental countries by the cubic metre. <A cubic 
metre of piled logs is called a Raummeter, the amount of 
actual solid wood contained in the pile being known as a 
Festmeter, the relation between these measurements being 

One Raummeter = 0°77 Festmeter. 
One cubic metre = 35°314 cubic feet. 


America.—Many systems are in use, the most common 
being the measurement by cords. A cord is a pile of logs 
8 feet long, 4 feet wide and 4 feet high. 


One cord piled logs = 128 cubic feet. 


Canada.— Measurements are also based upon the use of 
a cord of wood, in two ways, the first being the piled cord 
of 128 cubic feet and the second a solid cord which is the 
amount of solid wood contained in a piled cord, the relations 
being as follows : 


One piled cord = 128 cubic feet in the whole pile. 
One solid cord = 115 cubic feet of solid wood. 


86 WOOD PULP AND ITS USES 


This measurement of a solid cord has been estab- 
lished by the government of the province of Ontario, 
and was arrived at by means of a large number of 
special experiments carried out for the purpose of estab- 
lishing a common standard of measurement. It does 
not represent accurately the total amount of solid wood 
in an ordinary cord of 128 cubic feet, but it is a figure 
which has been selected as the standard for the payment 
of dues. 

In the province of Quebec a cord of pulp wood is con- 
sidered equal to 600 feet board measure, which relation was 
determined by a series of elaborate tests instituted for 
finding the amount of useful timber obtained from logs 
intended for lumber. This relation is used as a basis for 
calculating payments due to government, and does not 
necessarily represent the true equivalent, which varies 
according to the size of the log. 

The true measurement of the amount of wood in the logs 
is best secured by determining the actual cubical contents 
of each log separately. By this means all errors due to 
methods of piling the logs in stacks or to the varying 
lengths of the logs, is easily avoided. 

The importance of this question is easily shown in the 
following test made by an expert. 
~ Forty-two logs, each 16 feet long, were piled up carefully 
in a rack, the measurement of the wood being exactly three 
piled cords or 884 cubic feet.. The 16 feet logs, after being 
measured and piled, were cut in half and again piled. The 
stack was measured and then the logs were again halved, 
giving pieces 4 feet long, which were stacked up and 
measured. Finally the pieces were reduced to a length 


SOURCES OF SUPPLY 87 


of 2 feet, and the process of stacking and measuring 
repeated. The results are set out in Table I. 


AD Yahi be 
are a ee Dimensions of pile. eee Ratio. 
42 16 1G x16 sxe 4 3°00 100 
84 8 ae ape ws 2°81 93°7 
168 4 ct Wo ay hal: 2°69 89°7 
336 2 2X 12 X 13°83 2°59 86°35 


The effect of the closer packing rendered possible by the 
reduction of length in the log is plainly shown in this table. 
Thus 100 piled cords of wood measured in 16 feet lengths 
only measured 89°7 when reduced to 4 feet. The latter is 
a customary unit of measurement for pulp wood. Even in 
the case of wood cut in 8 feet or 4 feet lengths there would 
be a difference of four cords in the measurement, according 
to the length into which the logs are cut. This figure will 
naturally vary with different logs, and cannot be accepted 
as being applicable to all kinds of wood whether of large or 
small diameter. 

The practical effect is also shown in Table II. 


TABLE II. 

A Piled cords | No. of pieces - Extra 16 ft. logs No. of 
Pode 4 obtained required to yep Be required to give cubic feet 
eet, ; from 100 give piled Ee Ib cord. | the piled cord of | in piled 

; solid cords. cord. = stated lengths. cord. 

16 137 14 3,300 0 84°5 
8 128 30 3,080 1 90:0 
4 122 61 3,740 1¢ 940 
ae 18; 129 3,880 2 97-0 


88 WOOD PULP AND ITS USES 


This table is interesting as showing the exact result, in a 
practical manner, of reducing the length of the log, the 
difference being shown not only in the weight of the wood, 
but also in the very concrete fact that an extra log or two 
is required to make up the reduction. 


TABLE OF EQUIVALENTS. 


nati, | ous | gute | cord 
One cubic fathom is ~— 216 6°113 1:0687 
One cubic footis . 0:00463 — 0:283 000781 

| One cubic metre is 0°163 35°314 | — 0:276 
One cord is. : 0°5926 128 3°6224 — 


Woop Pup TREEs. 


The chief woods used for the manufacture of pulp are the 
species of spruce, fir and pines for sulphite and mechanical 
pulps, the aspen, poplar and other deciduous trees for soda 
pulps. ‘The conifers are also used for the manufacture of 
soda and sulphate pulps. For wrappers and fibre papers, 
hemlock is used in considerable quantity. 

The following is an alphabetical list of common woods, 
many of which, however, find no place at present in the wood — 
pulp industry. These are printed in italics in the name 
column. 


Common name. 


Acacia 


Ash : 
,, Mountain 
Ash 
Aspen 


Balsam . 
Basswood 
Beech 

Birch 
Chestnut . 
Cottonwood 
Orack Willow . 
Cypress . 

Klm 


Fir : : 
»> silver Fir 
(India) 


», silver Fir | 


(Hurope) 
Hemlock 


Hornbeam 


Larch 
Maple 
Paper Birch 
Pines : 
Black Pine . 
White Pine . 
Pitch Pine 
Poplar . i 
White Poplar 
Black Poplar 
Sallow (Willow) 
Sandalwood 
Spruce . f 
White Spruce 
_ Tamarac 
Willow 


Coniferee. 


SOURCES OF 


Botanical name. 


SUPPLY 


Robinia pseudacacia 
Alnus glutinosa 


Fraxinus excelsior 


Pyrus aucuparia 
Populus tremula 


Abies Fraseri 

Tilia Americana 
Fagus silvatica 
Betula alba 
Castanea sativa 
Populus monilifera 
Sahx fragilis 
Taxidium distichum 
Ulmus campestris 


Picea excelsa 
Abies pindrow 


Abies pectinata 
Abies canadiensis 
Carpinus betulus 


Larix Europea 
Acer dasycarpum 
Betula papyrifera 


Pinus austriaca 
Pinus strobus 
Pinus palustris 
Populus 
Populus alba 
Populus nigra 
Salix capreea 
Santalum album 
Picea excelsa 
Picea alba 
Larix americana 
Salix nigra 


Cone-bearing trees 


Deciduous or leaf-bearing trees 


89 


gs) 23, 
German. 35 2 3 
TQ: OD = aoe 
Schotendorn che lkoas 
Gemeine-erle 
(Roth-erle) "46 | 29°0 
Weiss-esche ‘65 | 40°8 
Eber-esche 54 | 34:0 
Zitter-pappel 
(Aspenholz) 50 | 31°3 
36 | 22°2 
Linde 45 128-2 
Rotbuche 75 | 46°8 
Birken-holz °64 | 40°0 
Kastanje "45 | 28:1 
Wollpappel “39 | 24:2 
Bruchweide oA yal 2Sc0 
Cypresse "45 | 28°3 
Steinlinde (Roth- 
rister) 69 | 43°3 
Fichte. ohre ‘49 | 30°0 
Tannenholz-Tanne | *46 | 29°0 
Tannelholz-Tanne | °49 | 30:0 
Schierlingstanne | °42 | 26°4 
Weissbuche 
(Hagebuche) 72 | 45:0 
Lorche "74 | 46°1 
Ahorn 52 | 32°8 
‘O0 Roe 
Kuefer. Nadelholz 
Schwarztohre 57 | 35°4 
Wehmuthskiefer 38 | 24:0 
Gelbkiefer “70 | 43°6 
Pappel ‘40 | 25°6 
Silberpappel ‘48 | 30-0 
Schwarzpappel 48 | 30-0 
Sahlweide iyi |b ai!) 
Santalholz ‘98 | 60°0 
Fichte (‘Tanne) 42 | 26°7 
Weisstanne AOr 20% 
Lorche *62 | 38°9 
Weide Hs Ey fa 
Nadelholz. 
Laubholz. 


90 WOOD PULP AND ITS USES 


The History of Mechanical Wood Pulp.—The possibility 
of using wood for papermaking seems to have been 
deduced from the Réaumur observation that wasps build 
their nests from partially decayed wood which they obtained 
from trees or timber. In 1765 J. C. Schaffer, a priest in 
Regensburg, published a book containing samples of paper 
made from many raw materials, and referring especially to 
wood, wrote: “it must be possible, though with different 
methods, to make paperstuff from wood and consequently 
use it instead of the ordinary rags for papermaking.” 

This is an interesting statement in view of the fact that 
nothing was then known of the use of alkalies or other 
chemical agents for reducing fibrous materials to pulp. 

Schaffer experimented with the material of the wasps’ . 
nest, with sawdust and shavings. From some seven or 
eight species of wood he made excellent sheets of paper, 
having regard to the means at his disposal. He published 
a second edition of his book, entitled, ‘‘ Simtliche Papier- 
versuche-Nebst 81 Mustern und 13 Kupfertafeln,” in 1772, 
and enlisted the services of a papermaker, Meckenhauser, 
to enable him to produce some better results. 

In 1800 Matthias Koops, a Dutchman, published a book 
which he printed on paper made from straw pulp and 
dedicated to King George Jil. He added an appendix to 
his work which was printed on paper made entirely of wood 
pulp, an idea suggested to him no doubt by the work of 
J.C. Schaffer. Koops was a man of some enterprise, for he 
also issued a work on paper made entirely from old waste 
paper, this being probably the first attempt to utilise old 
waste material for such a purpose. 

In 1840 Friedrich G. Keller, a young weaver of Haynich, 


SOURCES OF SUPPLY 91 


in Saxony, reading in a scientific journal of the great 
scarcity of rags as material for papermaking, resolved to 
keep his.eyes open for a substitute. In 1848 his attention 
was called to the remarkable paperlike appearance of the 
wasps’ nest, and recollecting that in his school days he had 
ground down cherry stones on an ordinary grindstone in 
order to make a cherry chain, he tried the effect of holding 
a piece of wood against the revolving stone. To his great 
delight the experiment was successful, and he collected the 
fibres so isolated from the wood and made a minute piece 
of paper. 

Keller continued his experiments, and in 1844 manu- 
factured about 2 to 3 cwt. of pulp, which was beaten up 
with rag pulp and made into paper. In 1845 he parted 
with the secret of his process, and disposed of it to Heinrich 
Volter for the sum of 700 thaler (£140) ! 

The progress of the new method was somewhat slow, but 
improvements, including the necessary treatment for refining 
the pulp, or removing the coarse chips, were introduced, 
and towards 1860 the process was put on a more satisfactory 
footing. In 1862 Volter was awarded the medal of the 
International Arts and Industries Exhibition in London. 

Between 1862 and 1865 seven or eight pulp mills were 
erected in Germany and Scandinavia and the manufacture 
of ground wood pulp on a large scale became an accomplished 
fact. 

History of Chemical Wood Pulp.—The early attempts of 
Koops in 1800 to utilise straw, and his few experiments 
with wood as substitutes for rag, may be regarded as the 
starting point in the history of chemical wood pulp. The 
materials were probably boiled with some crude soda ley 


92 WOOD PULP AND ITS USES 


and subsequently beaten into pulp. About this period soda 
ash, caustic soda, chlorine and bleaching powder and other 
chemicals had been introduced to the manufacturing world, 
so that the possibilities for reducing vegetable products to 
the condition of pulp were much greater. 


In 1857 Houghton patented a process for digesting wood 
with caustic soda at high temperatures in closed vessels. 

In 1868, Tilghmann, an American chemist, suggested 
the use of a solution of sulphurous acid gas. His early 
experiments were carried out in lead-lined vessels, but the 
work was abandoned owing to difficulties connected with 
the construction of suitable digestors. 

As Tilghmann was the inventor of a process which has 
become the basis of a large and important industry, the 
following précis of his first patent, as given by Mr. A. D. 
Little, may be quoted as having a peculiar interest :— 


The process of treating vegetable substances which contain fibres 
with a solution of sulphurous acid in water, either with or without the 
addition of sulphites or other salts of equivalent chemical properties 
as above explained, heated in a closed vessel, under pressure, to a 
temperature sufficient to cause it to dissolve the intercellular incrusting 
or cementing constituents of said vegetable substances, so as to leave 
the undissolved produce in a fibrous state, suitable for the manufacture 
of paper, paper pulp, cellulose, or fibres, or for other purposes, according 
to the nature of the material employed. 

I also claim as new articles of manufacture the two products 
obtained by treating vegetable substances which contain fibres with a 
solution of sulphurous acid in water, either with or without the 
addition of sulphites or other salts of equivalent chemical properties, 
as above explained, heated in a closed vessel, under pressure, to a 
temperature sufficient to cause it to dissolve the intercellular or 
incrusting constituents of said vegetable substances, one of said 
products being soluble in water, and containing the elements of the 
starchy, gummy, and saline constituents of the plants, and the 
other product being an insoluble fibrous material, applicable to the 


SOURCES OF SUPPLY 93 


manufacture of paper, cellulose or fibres, or to other purposes, 
according to the nature of the material employed. 

IT also claim the use and application, in the manufacture of paper, 
paper pulp, cellulose and fibres, of the fibrous material produced by 
treating vegetable substances which contain fibres with a solution of 
sulphurous acid in water, either with or without the addition of 
sulphites or other salts, of equivalent chemical properties as above 
explained, heated in a closed vessel, under pressure, to a temperature 
sufficient to cause it to dissolve the incrusting or intercellular con- 
stituents of said vegetable substances. 

LT also claim the use and application of sulphites or other salts of 
equivalent chemical properties as above explained, in combination 
with a solution of sulphurous acid in water, as an agent in treating 
vegetable substances which contain fibres, when heated therewith in a 
close vessel, under pressure, to a temperature sufficient to cause the 
said acid solution to dissolve the intercellular or incrusting constituents 
of said vegetable substances. 

I also claim the recovery and re-use of sulphurous acid and sulphite 
from the acid liquids which have been digested on the vegetable 
fibrous substances, by boiling said liquids or neutralising them with 
hydrate of lime. 


In 1872 Ekman had developed a process which was 
commercially successful, and this was introduced into 
England, at Ilford, Essex, about 1884, a mill being erected 
a few years later at Northfleet in Kent for the treatment of 
wood by means of bi-sulphite of magnesia. 

In 1876, Mitscherlich, a celebrated German chemist, 
experimented with sulphurous acid and devised a method 
for converting wood into pulp by cooking under low pressure 
for a long period, producing a half-stuff eminently suitable 
for certain classes of paper. 

Numerous and extensive modifications of the original 
Tilghmann sulphite process have resulted in the evolution of 
an industry typical of modern chemical engineering. Such 
modifications refer to details of working, more particularly 


94 WOOD PULP AND ITS USES 


to the type of boiler or digestor, to economy in the amount 
of sulphur used, to improving or varying the quality of 
the pulp, and to general efficiency, and are of subordinate 
historical interest. 

There has been a good deal of controversy as to the 
priority of original invention of this most important indus- 
trial development. It has always appeared to us that while 
Tilghmann is the pioneer from the technological stand- 
point, on the clear and specific claims of his patent above 
set forth, the practical and industrial pioneers were George 
Fry and his collaborator Ekman. Some years in advance 
of the bi-sulphite process (1869) Fry investigated the action 
of water only at high temperatures and pressures, paying 
particular attention to the volatile by-products of the 
complex reactions; and in this investigation secured the 
collaboration of the late Greville Williams, who identified 
furfural amongst the products of decomposition of the ligno- 
cellulose. 

Finding that the resolution of the wood under these 
conditions was limited by the influences of oxidation and 
condensation, it was then suggested by Fry to Ekman, who 
had become associated with these researches, to seek for a 
new chemical condition to antagonise these influences. In 
this path of logical though empirical evolution this group 
of pioneers may be held to have independently discovered 
the bi-sulphite process ; and Ekman, with George Fry, had 
the satisfaction of working the process to an industrial and 
commercial success at Bergvik, Sweden, then at Ilford, and 
lastly at Northfleet. 

The following is a chronological list of inventions for the 
preparation of pulp from wood by chemical reactions :— 


Year. 


1840 
1852 
1853 
18509 
1857 
1861 
1864 
1866 
1867 
1870 
1870 
1871 
1872 
1872 
1880 
1881 
1882 
1882 
1883 
1883 
1885 
1890 
1894 


SOURCES OF SUPPLY 


Name. 


Payen 

Coupier & Mellier 
Watt & Burgess 
Jullion 
Houghton 

Barre & Blondel 
Bachet & Machard 
Tilghmann 

Fry 

Ekman 

Dresel 

R. Mitscherlich 
Ungerer 
Rotter-Kellner 
Cross 

Francke 

Pictet & Brelay 
Graham 

Blitz 

Dahl 

Kellner 
Lifschutz 

Cross 


Process. 
Nitric Acid 
Soda 
Alkalis 
Alkaline salts 
Alkalis 
Dilute acids 
Acids 


Sulphurous Acid and salts 


Water at high temperatures 


Magnesium Sulphite 


Soda 


Sulphurous Acid and salts 


Soda 


Sulphurous Acid and salts 


Water and neutral sulphites 


Sulphurous Acid and salts 


Sulphurous Acid 


Sulphurous Acid and salts 
Alkalis and sulphites 
Sulphates and sulphides 


Electrolytic process 


Nitric and sulphuric acids 


Nitric Acid—dilute 


CHAPTER IV 
THE MANUFACTURE OF MECHANICAL WOOD PULP 


THe term “mechanical” or “ ground’’ wood pulp is 
applied to pulp which has been prepared by a mechanical 
process. The principle of the operation is merely the dis- 
integration of wood into fibres by means of a grindstone, 
the wood being brought into contact with the stone as it 
revolves. The conditions of manufacture are capable of 
considerable modification so that various grades and 
qualities of product are possible. 

Preparation of Wood.—The logs of wood, which have 
been brought to the mill from the timber limits or other 
sources, and which vary in length from 10 to 16 feet, are 
first reduced to a uniform length of 24 inches by means of 
large circular saws. 

The arrangements in a modern pulp mill for handling 
the logs and preparing them for conversion into pulp call 
for considerable skill and attention in order to produce the 
optimum result at minimum cost. 

The short pieces of wood are automatically conveyed to 
the ‘‘ barking”’ room and there deprived of the outer bark. 
The machine used for this purpose consists of a heavy 
circular iron disc enclosed in a strong casing. The 
disc is provided with three knives projecting from the 
surface of the disc in such a manner that when the short 
pieces of wood are pressed against the surface of the disc, 


MECHANICAL WOOD PULP ai 


as it revolves, they are completely denuded of the bark 
itself. A considerable proportion of wood is lost in this 
process, the amount varying from 15 to 25 per cent., 
according to the size and condition of the logs. The bark 
is generally burnt in special ovens and utilised as fuel. 

The clean pieces of wood may be employed for the manu- 
facture of either mechanical or chemical wood pulp and 
in practice the pieces are often sorted out, the clean wood 
free from dirt and knots being reserved for chemical pulp, 
and the inferior wood being converted into mechanical 
wood pulp. 

Cold-ground Pulp.—When the wood is ground into fibres 
in the presence of a large excess of water, a fine even pulp 
of uniform quality is produced. This pulp is known as 
‘“‘cold-ground’”’ in contradistinction to ‘ hot-ground”’ 
pulp, which is produced under the condition of high tem- 
perature (infra). 

The machine used for the manufacture of the cold ground 
pulp consists of a horizontal grindstone, usually 60 inches 
in diameter and with 27 inches breadth of face, mounted 
on a heavy vertical shaft and encased in a strong cast-iron 
circular box, as shown in Fig.14. Around the circumference 
of the box there are a number of recesses or “‘ pockets” 
in which the short 2 feet pieces of wood are placed. 
The wood is pressed against the surface of the rotating 
grindstone by pistons operating under hydraulic pressure, 
water being continuously applied to the surface of the 
stone so that the disintegrated fibres are carried away 
from the stone into storage reservoirs for subsequent 
treatment. | 

Hot-ground Pulp.—When the quantity of water flowing 

W.P. H 


98 WOOD PULP AND ITS USES 


to the grindstone is reduced to a minimum then the tempera- 
ture of the mass in contact with the stone rises rapidly on 
account of the friction, and the wood is thus ground to pulp 


WY. YG 
bp YU 


i 
ic : 


|, 


2 
Add ear — = eee IE? “4\ 
ct ke eee 


i \ 
Ls UML 


B 
Fic. 14.—View of Horizontal Grinder (A), with Section (B). 


under entirely different conditions. The fibres are readily 
torn away from the wood, and produce a pulp which is much 
coarser than the cold-ground pulp, the fibres being longer. 


MECHANICAL WOOD PULP 99 


The machine used for the manufacture of this pulp 
consists of a grindstone mounted in a vertical position on a 
horizontal shaft, operated by a water turbine. The stone 
is enclosed in a circular iron casing provided with “ pockets” 
into which the blocks of wood are placed. ‘The pieces of 
wood are forced against the surface of the stone by hydraulic 
pressure. 

The water is supplied to the grindstone in_ limited 
quantity, just sufficient being used to prevent the pulp 
from being burnt or spoilt. The temperature frequently 
rises to 150° ahr., owing partly to the greater pressure of 
the wood against the stone, and also by the conditions 
under which a limited supply of water is used. Pulp of 
this kind works freely on a fast-running news machine— 
that is, as the pulp and water flow on to the wire of the 
paper machine the water drains quickly and freely through 
the meshes of the wire, and thus makes it possible for the 
machine to be operated at a high speed. Many of the paper 
machines used for the manufacture of ‘‘ news”’ with pulp of 
this character can be run at a speed of 500 to 600 feet per 
minute. 

The quantity and quality of the pulp produced as con- 
trolled by the conditions of grinding depend on 

(1) The sharpness of the stones ; 

(2) The pressure applied to the blocks of wood ; 

(3) The temperature of the mass ; 

(4) The method of applying the wood to the stone. 

In general terms, the quantity of the pulp is increased by 
the use of sharp stones and the application of pressure, the 
yield being highest with wood treated by the hot-ground 
process. 

H 2 


100 WOOD PULP AND ITS USES 


The coarseness of mechanical wood pulp is merely a 
relative term, for it is possible to have a badly-ground wood 
pulp well screened, giving a coarse material of an even 
uniform grade, or, on the other hand, a well-ground wood 
badly screened giving a high-class pulp, spoilt by the 
presence of long chips or slivers which have not been 
removed. Such slivers in pulp are a fruitful source of 
“breaks ”’ on the paper machine, since they locally reduce 
the tensile strength of the web. Coarse pulp of a uniform 
grade does not produce “ breaks,’ but the fibres do not he 
closely in the surface of the paper, with the result that a 
large quantity of ‘‘ fluff’? is produced on the type of the 
rotary printing presses. | 

The output of a grinder is increased by sharpening the 
stone and by increasing the pressure applied to the blocks 
of wood. The effect of using sharp stones is clearly 
indicated by the following experimental results, obtained 
from two or three pulp mills :— 


Pounds of wood treated per hour. Ratios. 
Mill. 
Dull stones. Sharp stones. Dull stones. Sharp stones. 
440 680 100 155 
B 637 1064 100 167 
C 628 830 100 138 


The amount of wood pulp obtained from a grinder depends 
chiefly upon the pressure applied to the wood in contact 
with the stone, as shown by Kirchner’s elaborate experi- 
ments tabulated in the following table :— 


MECHANICAL WOOD PULP 101 


ere Consumption of 
Fite pecan ans power. per hour 
1 isto 1:25 
2 1°95 3°30 
3 2°60 a°16 
4 3°16 6°60 
9) 3°80 Eo2 
ae) 4°05 8°05 
6 4°40) 8°30 
fi a°0 7:92 


Yield of air-dry pulp H.P. required for 


24 hours for 1 ton 
air-dry pulp. 


86°0 
06°5 
47:0 
44°5 
44°7 
44°4 
49°4 
59°0 


The effective work of the stone under the conditions of 
the experiment is evidently reached when the pressure is 
5°5 lbs. per square inch, for at this point the power required 


for a given output is lowest. 


Kirchner gives the following interesting table showing 


the influence of the condition of the stones on various kinds 


of wood :— 


PRODUCTION OF PULP PER H.P. PER 24 HOURS UNDER 
DEFINITE EXPERIMENTAL CONDITIONS. 


Woad: Well sharpened stones 


Pine 
Fir 
Aspen . 
Poplar 
Lime . 
Birch . 
Willow 
Alder . 
Oak 


Lbs. of pulp. 


TRUDR SS 
bo ATOR Om 


|| 


Moderately sharpened 
stones. 
Lbs. of pulp. 


In a more complete series of trials Kirchner studied the 
relation between the power consumed with stones of varying 


102 WOOD PULP AND ITS USES 


degrees of sharpness in producing a stated quantity of 
pulp and the pressure on the surface of the stone. These 
trials were conducted with the hot-grinding process, and the 
amount of pulp produced per twenty-four hours was taken as 
100 kilos (say 220 lbs., or nearly 2 cwt.), the stones being 
worked under conditions giving this output. ‘Three stones 
—fine, medium and coarse grades—were selected for the 
experiment. The general results obtained show that as 
the pressure increased, the power required decreased up to 
a certain point, when any further pressure at once created 
a demand for greater power. This is admirably shown in 
the diagram Fig. 15, where the experiments with the three 
classes of stone are shown by the curves, A, fine; B, medium; 
C, coarse. 


The maximum output was obtained under the following 


conditions :— 
1 Pressure. F a Output in 
Stone. Lbs. per sq. in. Horse-power. 24 hours. 
A. Fine ; ‘ 4:2 4 220 lbs. 
B. Medium . F 12°6 2°4 220 lbs. 
C. Coarse. : 8°4 2 220 lbs. 


Excess of pressure is shown by the sudden upward turn of 
the curves, though with the coarse stone this point has not 
been reached. 

The immersion of the lower half of the stone in water 
had a remarkable effect on the results. 

The pressure can be increased enormously with a corre- 
sponding greater efficiency in the work of the stone, although 


MECHANICAL WOOD PULP 108 


Pressure in Ibs. per square inch of Surface 


ane VE aS 
bee mre 
aeee) uae 
ALE 


e) ~ 
“SUN0Y HZ J8d dng > WMI Z anb 07 pauinbas aH 


Fie. 15.—Curve for illustrating Power Trials. 


104 WOOD PULP AND’ Tis 30SiEs 


the power required does not vary much. This is shown by 
the curve D, which after a pressure of about 8 lbs. to the 
square inch assumes a horizontal position. » 

Kirchner found that the output per unit of area of the 
total grinding surface was almost proportional to the 
pressure. | 

The diagram in Fig. 15 represents the results of some of 
the more important tests. 

Curve A.—With a pressure of 14 lbs. per square inch a 
stone with fine surface required, in twenty-four hours, 74 
h.p., and with a pressure of 3 lbs. per square inch, 43h.p. 
The greatest production was obtained when the pressure 
reached 44 lbs. per square inch, when the power required 
to treat 2 ewt. of wood amounted to 4 h.p. 

Curve B.—This curve represents the work of an average 
stone which required 3 h.p. under a pressure of 44 lbs. 
per square inch. The power under a higher pressure 
of 14 lbs. per square inch was only 24 h.p. for the same 
production. 

Curve C represents the work of a coarse stone, the 
amount of power for a given production being reduced by 
the increase of pressure down to a certain point, after which 
any further increase of pressure required a greater amount 
of power. This is shown by the sudden rise of the curve 
when the pressure reached 13 lbs. per square inch. 

Kirchner in his interesting experiments pointed out that 
these tests show the relation between the production of 
pulp with different kinds of stone at different pressures, and 
shows that for a maximum output under economical condi- 
tions it is important to choose the right pressure for a 
given stone. In a further series of experiments he kept 


MECHANICAL WOOD PULP 105 


the stone partially immersed in a mixture of pulp and 
water. The results are shown in curves D and KE. 
Curve D.—With a pressure of 44 lbs. per square inch 
the power required for the production of 2 ewt. of pulp per 
twenty-four hours was 54 h.p. The gradual increase of 
pressure was accompanied by a reduction in the amount of 


Fic. 16.—Shaking Screen. 


power required, and with a pressure of 15 lbs. per square inch 
the power was reduced to 4 h.p. The practical effect of the 
greatly increased pressure was seen in the finer condition 
of the pulp. 

Screening.—The pulp from the grinders is carefully 
screened to remove all chips and insufficiently ground pulp. 
Many forms of apparatus are employed, but all are based 
upon the same principle, the use of plates perforated with 


106 WOOD PULP AND ITS USES 


fine slits or circular holes allowing all the finer pulp to pass 
through, but retaining all coarse pieces. 

The shaking screen shown in Fig. 16 consists of a horizontal 
shallow tray perforated with fine slits. The pulp, mixed 
with large quantities of water, flows on to the tray, which is 


Fic. 174.—Centrifugal Screen for Wood Pulp. 


kept in a violent state of agitation, and the fine pulp 
together with the water falls through the slits, while the 
coarse stuff is gradually forced along the surface of the 
tray and eventually falls over the edge into a trough of 
water or a travelling band conveyor. 

A flat screen is worked on a somewhat similar principle, 
but the motion of the plate is due to a violent agitation 


MECHANICAL WOOD PULP 107 


produced in a vertical direction instead of being to and fro 
in the horizontal direction. This produces a partial suction. 

The centrifugal screen, Fig. 17a, the latest form of 
apparatus for separating out the coarse pulp, is a round 
vessel, containing a circular screen built up of perforated 


ATM 


Te 


Uf. 


WE 


uN) 


A\\\ 


VAN 
ee 


- s- > > = SS a pete A EERE OS ert 5 


Fic. 178.—Section of Centrifugal Screen for Wood Pulp. 


plates, which rotates at a high rate of speed, the fine pulp 
being forced through the slits by centrifugal force. 

The capacity of a screen is usually expressed in terms of 
the weight of dry pulp obtained in a given period. Such 
figures are not of much value without details as to the size 
and number of the perforations per square foot of area, as 
the capacity is readily increased by the simple process of 
enlarging the slits or holes. 


108 WOOD PULP AND ITS USES 


Removal of Water.—When the pulp has been properly | 
screened, it is treated in a wet press machine in order to 
remove the large quantity of water with which it is 
mixed, and to produce a pulp fit for shipment to the 
paper mill. 

The dilute mixture is pumped continuously into a large 
vat in which rotates a hollow drum the surface of which is 
made of fine wire gauze. The pulp adheres to the drum, 
while the water is forced through the wire cloth and flows 
away into a trough fixed outside the vat. The thin skin of 
pulp is carried up above the surface of the water in the vat 
and is picked off by a travelling felt passing over a roller 
which is in contact with the drum. The thin sheet passes 
between small rollers, which squeeze out more water, and is 
then wound up in a continuous roll on a large wooden drum 
until it forms a thick sheet. This is removed at intervals 
either by hand or automatically. 

In the most approved form of wet press machine the 
thick sheet is cut off at regular intervals by a knife which 
falls automatically. The sheet of pulp is therefore always 
of uniform thickness and weight, provided reasonable care 
has been exercised in keeping the ratio of water and pulp 
fairly constant. From the wet press machine the pulp is 
obtained in the form of thick sheets containing about 75 per 
cent. of water. 

The sheets of pulp are finally submitted to pressure in 
powerful hydraulic presses which remove a further quantity 
of water and give a product containing 50 per cent. of air- 
dry pulp and 50 per cent. of water. ‘These sheets are 
packed in bales of 4 cwt. and 2 cwt. capacity, and then 
fastened up with stout iron wire and wooden battens. 


MECHANICAT, WOOD PULP 109 


Brown Woop Pu tp. 


In 1862 Lyman patented a process for submitting wood 
to the action of water at a high temperature, 160° C. In 
1870 Meyh found that when wood previously digested in 
this way was mechanically treated in the grinder it gave a 
tough long-fibred stock. Since that date large quantities 
of brown wood pulp have been produced for the manufacture 
of box boards. The wood is either simply steamed, in 
which case a dark brown product is obtained, or digested in 
water at high pressure when a lighter coloured paper is 
produced. 

Steamed Wood.—Logs of wood 12 or 16 feet long, or cut 
up in 2 feet lengths ready for the grinder, are packed into 
tall cylindrical boilers and steamed for twelve to thirty 
hours at a temperature varying from 120° to 160° C., the 
shorter period requiring a higher pressure. The water of con- 
densation containing organic acids and volatile compounds 
such as acetic and formic acids, ethereal oils, turpentine 
and resin is drawn off continuously, or at intervals. In 
modern practice such by-products are carefully preserved 
and refined, having considerable value. 

Wood Digested in Water.—A finer material of superior 
colour is produced when the wood is digested for twenty-four 
to thirty hours at a somewhat lower temperature in the 
presence of water, 60 lbs. pressure being the general 
practice. 

The boilers are usually cylindrical in shape, and of 
considerable length, erected in a horizontal or vertical 
position. Cast iron is regarded as more suitable, being 
less liable to oxidation and corrosion from the organic 


: 
i 
e 
z 
' 
3 
bs 
2 
a: 
: 
‘3 


cn yoguesenenye 


araayerioenyrny 


Fig. 1 


. 


—Digestor for manufacture of Brown Pulp. 


MECHANICAL WOOD PULP EEL 


acids produced during the operation. In Germany the 
practice obtains of lining the vessels with copper, and in 
one or two special cases digestors made of copper entirely 
have been built. ‘The price of a wrought-iron copper-lined 
digestor 5 feet diameter and 17 feet long is about £192, while 
a digestor constructed entirely of copper of about the same 
capacity would cost £450. 

Use of Brown Pulp.—Wood boiled in this way previous 
to grinding gives a material suitable for the manufacture 
of so-called ‘‘ leather board ’”’ used for box making. It is 
exceedingly tough and flexible, can be bent to almost 
any shape without cracking or splitting, and when made 
up into boxes is capable of resisting great pressure. It is 
also used for the manufacture of imitation kraft paper 
and for common paper pattern tissues. 


THe Estimation oF Mecuanican Woop Puup In PAPERS. 


The determination of the exact percentage of mechanical 
wood pulp in papers is obviously a matter of importance. 
Considerable attention has been given to this subject of 
recent years, and the various available methods may be 
briefly summarised. 

The use of the microscope as applied to the detection 
and estimation of different fibres in a sheet of paper has 
long been known. The first systematic application of 
quantitative methods to the vegetable fibres and manu- 
factured products is that of Vetillart, embodied in his 
treatise ‘‘Htudes sur les fibres vegetales textiles.’ 
Gottstein, in 1884, we believe, first suggested the quanti- 
tative microscopic method of counting the number of 


112 WOOD PULP AND ITS USES 


mechanical wood fibres in a given field of a specimen care- 
fully mounted using as a test for comparison specially 
prepared papers containing known percentages of mechani- 
cal pulp. 

Microscopic Analysis.—The paper is broken up into pulp 
by preliminary treatment with a weak solution of caustic 
soda, which is then thoroughly removed by means of hot 
water, and a number of slides are mounted for inspection, 
Herzberg’s staining reagent being used to colour the mass 
of fibres. Several slides are so prepared and carefully 
examined. The examination is best effected by bringing 
every portion of the slide into the field of view of the 
microscope, a record being made for each field of view 
as to the approximate proportion in which the fibres are 
present. This method is preferable to that frequently 
employed, of absolutely counting the fibres, but it demands 
a good deal of previous experience with pulp mixtures in 
which the proportions are already known. 

The usual staining reagents which may be used for 
differentiating fibres examined under the microscope are 
various aniline dyes, iodine solutions and iodine combined 
with dehydrating agents. The most useful reagent for 
general work is Herzberg’s iodine and zine chloride solution. 
The formule for the preparation of these reagents are as 
follows :— 


Winkler 
Potassium iodide. . 5 grammes. 
Iodine. . 1 gramme. 
Water. : : ; BP PAD Os 


Glycerine same 


99 


MECHANICAL WOOD PULP 113 


Herzberg— 
Chloride of zine 
Potassium iodide 
Iodine 
Water 


The colorations produced by these reagents are shown in 
the appended table, but the colour reaction varies with the 
purity of the fibre, and the percentage of moisture present 
in the small quantity placed on the microscope glass. 


20 grammes. 
rg A! 

O'l gramme 
5 grammes. 


Micro-CHEMICAL REACTIONS OF FIBRES. 


Coloration produced. 


Fibres. Magnesium 
chloride, 


iodine solution. 


Zine chloride, 


Iodine solution. iodine solution. 


Cotton, hnen,hemp| Brown Wine-red Reddish brown 


Esparto, straw, 
bamboo, celluloses 


Wood celluloses 


Manila hemp 


Mechanical wood 

pulp, jute . ; 
Unbleached Ma- 
nila, straw (par- 
tially boiled) 


Grey to grey- 
ish brown. 

Colourless. 

Grey, brown, 
or yellowish 


brown. 


Yellow. 


Yellow. 


Blue to violet, 
or blue to 
greyish vio- 
let 

Blue to bluish 
violet 

Dark yellow 
or greenish 
yellow 


Yellow 


Yellow. 


Bluish violet 


Light brown 
to red 

Yellow, green- 
ish yellow 


Yellow 


Yellow 


Colour Methods of Analysis—Various simple colour 


reactions are known, all of which afford a rough indication 

of the proportion of mechanical wood pulp in papers. In 

1882, Gaedicke proposed the manufacture of a series of 

standard papers containing varying proportions of 

mechanical wood, the first paper in the series to consist 
W.P. 1 


114 WOOD PULP AND ITS USES 


of pure sulphite, and the last paper of the series containing 
95 or 100 per cent. of mechanical wood pulp. On each of 
the standand papers a solution of aniline sulphate of known 
strength produced a yellow coloration, the intensity of 
which was in direct proportion to the amount of mechanical 
wood pulp. Equal coloration on the standard, and an 
unknown paper could then be recorded as evidence of equal 
amounts of mechanical wood pulp, and this reaction would 
furnish a means for measuring the percentage of ground 
wood pulp in the paper. The following reagents can be 
employed for this purpose. 

Aniline Sulphate.—4 grammes of the salt dissolved in 
100 c.c. of water. This reagent gives a yellow colora- 
tion when placed on paper containing mechanical wood 
pulp. 

Phloroglucinol.—2 grammes of phloroglucinol are dissolved 
in 100 ¢.c. alcohol and 50 ¢.c. concentrated hydrochloric 
acid added. The solution should be kept in the dark. 
Gives a pink to crimson coloration more or less intense 
according to the proportion of mechanical wood present. 

Ferric Ferricyanide.—Dissolve 1°6 grammes ferric chloride 
in 100 cc. of water. Dissolve 3°3 grammes. potassium 
ferricyanide in 100 c.c. of water. Equal quantities of the 
solutions to be mixed and used only when required. Gives 
a Prussian blue colour with mechanical wood pulp. 

Wurster’s Reagent.—2 grammes of dimethyl para- 
phenylenediamine dissolved in 100 c.c. of water. Gives a 
deep red colour with mechanical wood pulp and other 
lignified fibres. 

Phenol.—A dilute solution of phenol gives a greenish 
blue colour with mechanical wood pulp. 


MECHANICAL WOOD PULP 116 


Chemical Methods of Analysis.—Ruller in 1887 suggested 
a method based on the solubility of cellulose in ammoniacal 
copper oxide. The paper, having been suitably broken up 
into pulp, is treated with the solution, and the cellulose 
dissolves fairly quickly, leaving the mechanical wood pulp 
as an insoluble residue to be filtered, washed, dried, and 
then weighed. ‘The cellulose estimations obtained by this 
process are not very satisfactory. 

The reaction of the ligno-celluloses with iodine has also 
been suggested as the basis of a method of quantitative 
analysis. ‘The paper reduced to the condition of pulp is 
allowed to remain in contact with a definite quantity of 
iodine dissolved in potassium iodide. After standing twenty- 
four hours the amount of iodine left in the solution is 
determined by titration with sodium thiosulphate, the 
amount of iodine absorbed being a measure of the amount 
of mechanical pulp present. 

Godeffroy and Coulon proposed a method dependent upon 
the reaction between lignified wood fibre and chloride of 
gold. The paper is torn up into fine shreds, divided into 
two equal portions of convenient weight, and boiled for 
about ten minutes in a 10 per cent. solution of aqueous 
ammonia, then thoroughly washed and dried. One portion 
is burnt for the determination of ash. The second portion 
is extracted with a hot alcoholic solution of tartaric acid, 
dried, and then successively extracted with alcohol and 
ether. The residue left is then boiled for about fifteen 
minutes with a dilute solution of gold chloride, the latter 
filtered and removed by washing. The dried fibre containing 
the adherent reduced gold is then burnt and the weight of 
ash and gold ascertained. The difference between the ash 

1 2 


116 WOOD PULP. AND ITS USES 


previously weighed and the weight of ash and gold 
together, measures the quantity of gold reduced to a 
metallic state, and the latter is an indication of the 
proportion of lgnified fibre in the sample of paper. 
Numerous experiments conducted by Godeftroy and Coulon 
show that under these conditions 100 parts of mechanical 
wood pulp per se will reduce 21°2 parts of gold. 

Benedikt proposed a method based upon the reaction 
between lignified fibre and hydriodic acid, the products of 
decomposition being added to silver nitrate, with the 
precipitation of silver iodide. The weight of dry silver 
iodide is taken as a measure of the mechanical wood pulp 
present. 

The action of chlorine gas on lgno-cellulose is also 
suggested as the basis of a quantitative method of analysis 
for mechanical wood pulp. ‘The paper is boiled in a weak 
solution of carbonate of soda, washed thoroughly with weak 
acetic acid, and then with hot water until quite neutral. 
The paper is pressed and exposed in a damp condition to 
the action of pure washed chlorine gas. After complete 
chlorination the excess cf chlorine gas is blown out of the 
vessel, and a known volume of water added to the bleached 
pulp. The quantity of hydrochloric acid in the aqueous 
solution is determined by titration with standard soda 
solution. 

The acid equivalent to one gramme of various pulps is as 
follows :— 


Mechanical wood pulp . 4°4 c.c. normal alkali 
Aspen mechanical pulp . 35 ce ,, fp 
Unbleached sulphite O76 CCares if 


Bleached sulphite Hes: 0376; Ce. ‘ 


MECHANICAL JVOOD PULP 117 


The most recent method devised, by Cross and Bevan 
is based upon the well-known phloroglucinol reaction. A 
weighed quantity of the paper previously broken into pulp 
is placed in a solution of standard phloroglucinol, the strength 
of which has been previously found. The quantity of 
phloroglucinol in solution before and after immersion of the 
fibre is determined by titration with formaldehyde. It has 
been shown that all lignified fibres possess what may be called 
a constant ‘‘ phloroglucinol absorption value.” 

The details of the process are as follows :— 

Two grammes of the material are dried at 100° C. 
and then weighed. The weighed amount is transferred to 
a dry flask, covered with 40 ¢.c. of phloroglucinol solution 
(made by dissolving 2°5 grammes of pure phloroglucinol in 
500 e.c. of hydrochloric acid of 1:06 sp. gr.), shaken and 
allowed to stand for some hours, preferably all night. The 
liquid is then filtered through cotton-wool placed in the 
neck of a funnel. The filtrate is next titrated, 10 ¢.c. being 
mixed with 20 c.c. of hydrochloric acid of 1°06 sp. gr. and 
heated to 70° C. Standard formaldehyde solution (made 
by dissolving 1 cc. of 40 per cent. formaldehyde in 
500 c.c. of hydrochloric acid of 1°06 sp. gr.) 1s now added, 
1 c.c. at a time, two minutes being allowed to elapse between 
each addition. 

As indicator of the presence of phloroglucinol, a piece of 
cheap newspaper is used. A red stain is produced in the 
presence of free phloroglucinol when a drop of the liquid 
is allowed to fall on the paper. 

Towards the end of the titration the stain gradually 
takes longer and longer to appear on the paper, and finally 
it is necessary to carefully dry the paper before a Bunsen 


118 WOOD PULP AND ITS USES 


flame. The end of the filtration is indicated when the 
stain is no longer perceptible. 

10 c.c. of the original phloroglucinol Solin are then 
titrated under exactly the same conditions, the amount ab- 
sorbed by the ligno-cellulose being obtained by the difference 
between the two figures. This phloroglucinol absorption 
value is expressed as a percentage on the dry weight of the 
ligno-cellulose. 

The following values have been obtained: Wood flour, 
7°9; mechanical wood, 6°71; jute (best quality), 3°98 ; jute 
(average quality), 4°26; sulphite wood pulp, 0°75; and 
cotton, 0°2 per cent. of phloroglucinol. 

For the calculation of the mechanical wood in paper the. 
following formula is used, 8°0 being the absorption value 
for mechanical wood, and 1°0 that of sulphite pulp, p the 
absorption value of the dry ash-free sample, and H the 
percentage of mechanical wood in the paper. 


100(p — 1:0) 


ee a reeay aT 


Sources of error, and the conditions necessary for the 
most constant and accurate results are :— 

1. The purity of the phloroglucinol used. The standard 
solution is made from a weighed amount of this substance. 
It is therefore necessary to ensure its purity. 

2. The absorption value is influenced by the concentration 
of the phloroglucinol solution. The quantities to be used are 
2 orammes of paper and 40 ¢.c. of phloroglucinol solution. 

3. Generally, it is unnecessary to remove sizing material 
from the paper before the determination. In the case, 
however, of large quantities being present, its extraction 


MECHANICAL WOOD PULP 119 


(by warming with a mixture of alcohol and ether) is to be 
recommended, the reaction taking place more rapidly. 


EXAMPLES. 
Qi: Phloroglucinol | Mechanical 
eee c Ash. Sizing. sorvti 
Newspaper. Per cent. Ber ennt napa cab ate: 
Times . : 8°4 1°5 2°14 16°35 
Daily Telegraph 2°4 15 2°40 20°0 
Tribune. 10°2 1°5 5°23 60°4 
Daily Graphic : 15°1 1°5 5°0 5771 
4d. paper (white) . 1°5 15 6°62 80°3 
4d. paper (pink) 2°0 1°5 6°32 76-0 


CHAPTER V 
CHEMICAL WOOD PULP 


Tue term ‘ chemical,’ in contradistinction to the term 
‘mechanical,’ is applied to wood pulp prepared by a 
chemical process in which the isolation of the fibre is 
effected by treatment of the wood with suitable solutions. 
The resultant product is a more or less pure form of cellu- 
lose, differing very materially from the fibre of the 
mechanical process. In the latter case the pulp consists of 
the raw wood in which the constituents are unchanged 
except in form and shape, whereas the chemical pulp 
is entirely different in composition from the original 
material. This is shown in an analysis given by Griffin 
and Little :— 


Spruce wood. Spruce cellulose. 
Moisture 11°5 67 
Ash : : 0:3 0°5 
Cellulose : 53°0 Soi 
Lignin, etc. . 35°2 3°1 
100-0 100-0 


The methods employed for the preparation of cellulose 


CHEMICAL WOOD PULP 121 


from wood are of two kinds, namely, the acid, of which the 
so-called sulphite process is typical, and the alkaline, 
exemplified by the well-known soda process. 

Preparation of Wood.—Whichever system is used the 
preliminary operations for preparing the wood are the same. 
The logs are cut into lengths of two feet, the bark com- 
pletely removed by the methods described in the chapter on 
Mechanical Wood Pulp, and subsequently cut up into small 
chips by special machinery. 

For the best qualities of pulp the knots in the wood 
are cut out, or as an alternative the chips of wood are 
carried by means of a travelling band into a sorting room 
and all the knots and faulty pieces of wood removed by 
hand. 

Sulphite Process.—In general terms this consists in sub- 
mitting the wood to the action of sulphurous acid and its acid 
salts in closed vessels at high pressure for definite periods 
of time. The quality of the product can be varied to almost 
any extent by the conditions of treatment, that is by varying 
the strength of liquor, the steam pressure, and the period 
of time occupied in digestion. This may be shown by a 
study of the several qualities of sulphite pulp available for 
paper-making. 

Quick Cook Process.—This term is applied to pulp 
prepared by digesting the wood at a high pressure of 80— 
100 lbs. per square inch for a period of eight to nine 
hours. If the operation is carried out to an extreme limit, 
using the strong liquor, a soft pulp is obtained of good 
colour which bleaches very rapidly with a small proportion 
of bleaching powder. Ifon the other hand the treatment is 
carried out with a minimum quantity of liquor just sufficient 


122 WOOD PULP AND ITS USES 


to produce complete disintegration of the wood, then the 
pulp obtained is of a reddish colour, not easily bleached, 
but which is characterised by great strength and toughness. 
The latter kind of pulp is eminently suited for the manu- 
facture of news and wrapping papers, in which strength 
is of primary importance, whereas the former quality of 
pulp produced by excessive boiling is more suitable for 
book papers and writings in which colour is of greater 
importance. 

Slow Cook Process.—This method differs radically from 
the quick process, in that the pressure is seldom allowed to 
exceed 15 lbs., while the time of boiling occupies thirty to 
forty-eight hours. Moreover, the heat is applied by means 
of steam passed through lead coils so that the condensed 
steam produced does not accumulate in the digestor itself. . 
The pulp obtained in this case is of excellent quality and of 
ereat strength, being particularly adapted for the produc- 
tion of papers such asimitation parchments. It is frequently 
described as ‘‘ Mitscherlich” pulp from the name of the 
inventor of the process. 

Sulphite Liquor.—The chemical solvent used in the 
bi-sulphite process is a solution of bi-sulphite of lime con- 
taining a certain proportion of free sulphurous acid. It is 
prepared by burning sulphur or pyrites rich in sulphur, in 
suitable ovens, and passing the sulphurous acid gas obtained 
through tanks containing milk of lime, or through towers 
containing blocks of limestone moistened with water. 
Many different systems are in use for burning the sulphur 
under regulated conditions, and for producing a liquid 
containing definite proportions of lime or magnesia 
sulphites and free sulphurous acids. The proportions 


CHEMICAL WOOD PULP 123 


vary in different mills, the following being typical of 
many :— 


Free sulphurous acid . ; . 2°03 per cent. 
Combined sulphurous acid . oO a 
Lime . : : 20:39 


The quantity of sulphur required per ton of finished pulp 
varies from 250 lbs. to 400 lbs. Considerable attention is 
now given to methods by means of which the sulphurous 
acid gas which comes away from the digestors during the 
operation is utilised, thereby reducing the amount of 
sulphur actually required per ton. 

Waste Sulphite Liquors.—The waste liquors discharged 
from the boilers when the wood has been boiled are at 
present thrown away. Many attempts have been made to 
recover the by-products, but no system has yet been intro- 
duced for the recovery of the sulphur on a large commercial 
scale likely to be remunerative, or for the manufacture of 
by-products having any practical value. 

The problem has long been a serious one, for in 1894 a 
prize of 10,000 marks was offered in Germany for a prac- 
ticable method of preventing the pollution of streams by 
the waste liquor of sulphite mills, but no serviceable process 
has been devised. The volume of liquor is so large, that 
the difficulties are greatly increased. One ton of air-dry 
pulp gives about 2,500 gallons of acid liquor which diluted 
with a sufficient quantity of wash waters required for 
cleaning the pulp blown from the digestors is increased to 
about 10,000 to 12,000 gallons. 

Hoffmann* gives the analyses of several waste liquors as 
follows :-— 


** Hoffmann, C., Practisches Handbuch der Papier Fabrikation, 1897. 


124 WOOD PULP AND ITS USES 


ANALYSES OF SULPHITE PuLP WASTE LIQUOR. 


Total solids. 
Loss on ignition . 
Ash 

Total sulphur 


Free sulphur dioxide 


(SOz) 
Sulphite radicle (SO,) . 
Sulphate radicle (SO,) q 


Oxygen consumed 


8 2°0 


68°0 


Grammes per litre. 


bo 


52°0 


3 4 5 
85'0 93°0 92°0 
69°0 81:0 — 
16:0 12°0 = 
— — 9°2 

2°9 2°6 3°8 

67 Is 3°8 

4°8 2°7 1°93 
50°0 60:0 — 


The characteristic constituent of these liquors is’ the 
lignone-sulphonic acid (calcium salt) resulting from the 
specific interaction of the bi-sulphites with the aldehydic or 
quinonic complex of the wood or ligno-cellulose. 

The free lignone-sulphonic acid gives a characteristic 
reaction with gelatin, precipitating a colloidal viscous 
mass, which may be re-dissolved in weak alkaline- liquids, 
and when so re-dissolved has been employed in engine- 
sizing papers. The reaction with gelatin suggests its 
employment as a “tanning” agent in the manufacture of 


1 Lindsay and Tollens, Annalen, 267—341; H. Seidel, Zeitschr. 


Angew. Chem., 1900; Suringar Diss. Gottingen, 


1892; Klason. 


Chem. Ztg., 1897, 261; Seidel und Hanak. Mitt. Techn. Gew. Mus. 


1897-—8. 


CHEMICAL WOOD PULP 125 


leathers ; and acertain amount of the liquor is being utilised 
in this industry. 

In addition to the characteristic lignone-sulphonic acid, 
and excess of sulphurous acid, free and combined, the 
liquors contain a certain proportion of carbohydrates ; 
and hence after treatment of the liquors to bring about 
the necessary conditions, a process of fermentation is 
induced by the introduction of yeast, from which alcohol 
results. 

The subject of the composition and utilisation of sulphite 
liquors has, in fact, been extensively studied, and the 
following brief account of the processes patented during the 
last thirty years may be added. Cross and Bevan observed 
the reaction of the lignone sulphonates and patented the 
production of the insoluble colloidal compound and its use 
in the engine-sizing of papers. [E. P. 1548, 1883.] 

Mitscherlich revived the method of mixing gelatine or 
some cheaper form of animal size with the spent lye, in 
order to obtain a tannin size suitable for sizing paper in 
the beating engine. By using ordinary rosin size in con- 
junction with the new product he claimed a reduction in the 
cost. [D. R. P. 98,944—5.] | 

Ekman obtained a substance which he called “ Dextron ”’ 
by concentrating the liquors to 34° Be. and adding magne- 
sium sulphate. ‘The product was applied to the dressing of 
textile fabrics to render them partially waterproof and to 
secure them from mildew. [D. R. P. 81,643.] 

Dr. Frank proposed the addition of milk of lime to the 
waste liquor so as to separate the sulphites as calcium 
sulphite, the remaining liquid to be discharged as com- 
paratively harmless. 


126 WOOD PULP AND ITS USES 


The presence of the large proportion of organic matter in 
the liquor has suggested the basis of a scheme for the 
manufacture of compressed fuel. Attempts have been 
made to concentrate the waste liquors to a syrupy con- 
sistency and to employ this paste in conjunction with 
sawdust, coal dust or charcoal for the production of 
briquettes. 

Dorenfeldt patented a modification of the ordinary calcium 
bi-sulphite process which appeared to make the subsequent 
treatment of the spent digestor lyes a more profitable 
undertaking. Sulphate of soda was added to the usual 
bi-sulphite of lime liquor, whereby a precipitate of sulphate 
of lime was obtained, and a solution of bi-sulphite of soda. 
The sulphate of lime was filtered off and sold as “ pearl 
hardening” for the loading of paper, and the bisulphite of 
soda used for digesting wood. The soda was recovered by 
concentration and incineration and afterwards converted 
into caustic soda by the ordinary methods. 

Drewson proposed to heat the stronger waste liquors 
with lime under pressure, the resultant product calcium 
mono-sulphite being subsequently converted into the soluble 
bi-sulphite with sulphurous acid gas. The cost of the 
process and the impurity of the regenerated liquor are 
conditions which have prevented the development of a 
likely scheme for recovery. [D. R. P. 67,889. ] 

Destructive distillation has been experimentally tried, 
but the yield of useful products is much too low. The 
formation of oxalic acid by fusion of the concentrated liquor 
with alkali has also been proved, but the quantity obtained 
was too small to render any operations on a large scale 
commercially possible. 


CHEMICAL WOOD PULP 127 


b] 


a substance obtained by converting the 

lignone-sulphoniec acid into a soda salt, has been success- 
fully applied in mordanting woollen goods. Its use in this 
direction is naturally very limited, and offers no induce- 


‘“¢ Lignorosin,’ 


ment to manufacture on a large scale. 

The utilisation of the lignone-sulphonates by treatment 
with nitric acid Wy the manufacture of colouring matters is 
suggested by the reactions of the lignone constituents of 
wood with nitric oxides. The treatment of these substances 
with nitric acid gives a series of orange and yellow dyes 
which produce bright shades on wool and silk. Fusion of 
‘“‘lionone”’ with sodium sulphide and crude sulphur gives 
a sulph ir dye that colours cotton dark green, changing to 


4 


certgin purification of the waste sulphite liquor to eliminate 
the/éxcess of mineral sulphites, and a certain proportion of 
uble iron compounds, which produce discoloration when 
used in association with ordinary tanning. Considerable 
activity is being shown in this direction, with some prospect 
of success. 

Robeson has patented a process for tanning skins and 
hides in which a liquor containing a compound of sesqui- 
oxide of aluminium or some other base with the practically 
unchanged organic matter of waste sulphite liquors is 
employed. The lye is treated with the sesqui-oxide in 
conjunction with an acid capable of precipitating mineral 
matter from the liquor. 

As 25 per cent. of the solid residue in sulphite liquors 


' Pollution of Streams by Sulphite Pulp Waste. E. B. Phelps, 
U.S.A. Geological Survey Dept. . 


128 WOOD PULP AND ITS USES 


can be removed from solution by the hide powder test, the 
process seems promising. 

A writer in the Wochenblatt has suggested the incorpora- 
tion of the lyes with soap, claiming that the resinous and 
olucose substances present together with the mineral salt, 
would produce a new soap of good lathering and cleansing 
properties. 

Knosel suggests a process for mixing the sulphite lye 
after suitable concentration with an equal weight of phos- 
phate of lime, thereby obtaining a solid and soluble 
compound to be used as a fertiliser, the manurial qualities 
of the phosphate of lime being increased 380 per cent. 

Elb adds formaldehyde to the sulphite liquors during 
concentration and obtains an adhesive substance, clear and 
transparent, soluble in water. The formaldehyde is said 
to prevent the separation of salts during evaporation. 


Alcohol from Waste Lye.—The most recent and interesting 
attempt to deal with the waste sulphite liquors is seen in 
the experiments now being carried out on a large scale 
in Sweden for the production of alcohol. The process is 
being worked on a fairly large scale under EKkstrom’s 
patents at Skutskar in Sweden, the average yield of alcohol 
being 60 litres per ton of cellulose, no less than 54,000 
litres having been produced during 1909. 

In 1819, Braconnet observed that, by the action of 
sulphuric acid on wood, grape sugar was formed, which 
could be fermented to yield alcohol. 

In 1898, Simonsen obtained 60 litres of spirit from one 
ton of wood by this acid process. 

In America, Ewen and Tomlinson, acting on the 


CHEMICAL WOOD PULP 129 


suggestion of Classen, obtained 78 litres of spirit by the 
action of sulphurous acid on wood. 

In 1891, Lindsay and Tollens found 1°2 per cent. of fer- 
mentable carbohydrates in the dry solids of waste sulphite 
liquor, and obtained about 60 litres per ton of cellulose. 

‘'wo processes have now been patented in which the lyes 
are first neutralised by carbonate of lime. In Wallin’s 
method ordinary lime is used for neutralising the liquor, 
and in EKkstrom’s system the waste hme sludge of the 
sulphate cellulose mills is employed. Schwalbe states that 
the neutralisation sludge obtained, after the process, con- 
tains sufficient calcium sulphite to effect a saving of 40 per 
cent. of the sulphur required for boiling wood. 

The volume of liquor to be treated amounts to 10,000 
litres for every 100 tons of cellulose and the dry precipitate 
obtained on neutralising amounts to 15 tons. The liquid, 
after being neutralised, is cooled, aerated, then fermented 
for 72 hours at a temperature of 75° C., by means of yeast, 
and afterwards distilled. The alcohol obtained contains 
considerable proportions of methyl alcohol, aldehydes, 
furfural and acetone. It may be noted that this process, 
while interesting as showing the possibility of obtaining 
useful products from the waste liquor, does not deal with 
the serious problem of the prevention of pollution of streams 
by the discharge of the waste liquor. 

The direct recovery of the original sulphur has not yet 
been evolved as a satisfactory process. Hvaporation and 
combustion of the concentrated lye means a large loss of 
sulphur, and a method for the regeneration of the latter 
from organic sulphur compounds has yet to be discovered. 
Obviously this is the correct solution of a difficult problem, 


W.P. s 


130 WOOD PULP AND ITS USES 


as it might avoid the formation of a large quantity of 
by-products which find no useful application in paper- 
making or any industrial operations. 


Washing and Finishing.—The pulp discharged from the 
digestor is thoroughly washed with water for the removal 
of the spent liquor, and then subjected to a careful screening 
in order to remove incompletely digested pieces of wood 
and any dirt which may be present. 

This is effected by screens of various kinds, all based 
upon the same principle, though differing in construction. 
The apparatus most frequently employed is the flat screen, 
consisting of a heavy cast-iron shallow tray fitted with brass 
plates which contain fine slits. The tray is kept ina state of 
violent agitation, so that the mixture of pulp and water 
flowing into the tray is also continuously shaken. By this 
means the pulp is easily screened, the pure material finding 
its way through the slits, while the coarse lesser-cooked 
material remains on the surface of the screen. 

The pulp is then sorted up into various qualities, the 
coarse residue being sold at a low price as “‘ screenings.” 

The fibre passing through the screens, being mixed with 
a very large volume of water, is then subjected to a process 
whereby the water is removed, and the pulp obtained in the 
form of moist sheets, containing about 50 per cent. of 
moisture. 

Sulphite pulp is usually prepared for export in the form 
of dry sheets, and these are produced by treating the pulp 
in a somewhat different manner. The wet mixture is con- 
verted into dry sheets by means of a machine which closely 
resembles an ordinary paper-making machine—that is, the 


CHEMICAL WOOD PULP 131 


mixture of pulp and water is passed over a horizontal travel- 
ling wire and the thin sheet of pulp so obtained drawn 
through heavy rollers, which squeeze-out a large proportion 
of the excess water, and finally over drying cylinders heated 
internally by steam. 

Soda Process.—The alkaline treatment of wood for the 
manufacture of soda wood pulp is similar to that used for 
the manufacture of esparto pulp. The wood, in the form 
of small chips, is heated in large digestors with a solution 
of caustic soda. The non-fibrous constituents of the wood 
are completely dissolved, and a brown-coloured pulp is 
obtained. The spent liquors are preserved and the soda 
recovered, to be used over again as required. 

The soda process is one capable of general applica- 
tion, being utilised for woods and fibres which cannot easily 
be treated by the sulphite process, which latter is usually 
confined to the treatment of the coniferous woods. In the 
early days of the manufacture of wood pulp, when spruce 
was available in large quantities, wood pulp was almost 
exclusively prepared from spruce by the sulphite process. 
The present scarcity of spruce and the high price now 
ruling have compelled manufacturers to give their attention 
to other classes of wood, and the American Government, for 
example, are making investigations as to the use of woods 
which have hitherto been regarded as unsuitable. Such 
investigations will, no doubt, lead not only to the introduc- 
tion of woods other than spruce, pine, and poplar, but also 
to modifications in the various methods of treatment. 

All kinds of wood and other fibrous material may be 
converted into pulp by this process. Caustic soda combines 
with the acid products derived from the non-fibrous 

K 2 


132 WOOD PULP AND ITS USES 


constituents of the wood until the alkali is neutralised, so - 
that the insoluble portion of the wood left is cellulose in a 
more or less pure condition, containing much less resin 
than the pulp obtained by the sulphite process. 

The practical operations are simple enough. The wood 
is barked in the usual manner and cut up into small pieces 
by the same machinery as that employed for the sulphite 
process. ‘The wood is digested for six to eight hours in a 
solution of caustic soda having a strength of about 20° Tw., 
at a pressure of 100—150 lbs. per square inch. ‘The con- 
ditions of treatment are varied according to the nature of 
the wood and the requirements of the paper manufacturer. 
For pulp that will bleach readily the process of digestion is 
carried out to a greater extent than for pulp which is required 
in the manufacture of wrapping papers. The yield of pulp 
and the quality are influenced by these conditions. 

Some interesting experiments were made by Beveridge 
showing the precise influence of varying factors. He made 
three sets of trials as follows :— 


Constant condition. Variable. 
1. | Time and strength of caustic | Pressure varied. 
2. | Pressure and time Strength of caustic varied. 


3. | Pressure and strength of | Time varied. 
caustic ; 


The results were :— 

(1) The increase of pressure resulted in a diminution of 
yield, the quantity of pulp obtained being reduced 
considerably. 


OHEMICAL WOOD PULP 133 


(2) The excess of caustic soda caused rapid diminution 
in the yield of cellulose. 

(3) The gradual exhaustion of the caustic soda by a pro- 
longed digestion prevented such serious diminution 
of yield. 

From a practical standpoint the chief consideration is 

the nature of the wood, and De Cew gives the following 
results as showing the usual conditions of treatment :— 


rast: Weight of air- 
W ees Caustic soda ape ont Yield air-dry 
Wood. ee ft used pcr from one pulp. 
= Than cord. cord. Per cent. 
ane Lbs. 
1. Yellow Birch . 3630 641 1610 44°4 
2. Soft Maple : 3520 641 1560 44-4 
3. White Birch . 3190 603 1490 46°7 
4, Poplar ‘ ; 2350 603 1150 49-0 
5. Bass wood . ; 2325 603 1135 49-0) 
6. Black Spruce. 2250 678 1000 44°5 
7. Hemlock . : 2300 716 970 42°2 


The variation in the quality of the pulp produced by the 
soda process is a striking illustration of the necessity for 
an exhaustive study of the whole process of chemical wood 
pulp manufacture. ‘The most interesting developments are 
seen in the suggestion that the highest yield of pulp consis- 
tent with the complete removal of the non-cellulose portion 
of the wood is best obtained by modifications in the process, 
which reduce the action of the caustic soda on the cellulose 


134 WOOD PULP AND ITS USES 


toaminimum. Suggestions have been made in this direc- - 
tion not only with the soda process, but with all chemical 
methods by the idea of using wood in a perfectly dry 
condition; by having a vacuum inside the digestor, so 
that the air is largely removed from the pores of the 
wood, enabling the liquor to penetrate quickly; by the 
use of superheated steam for the boiling operation; and 
SO on. 

All these improvements are in the right direction, because 
the wood is not subjected to a more severe treatment, but 
is merely placed under more favourable conditions for the 
action of the caustic soda. The result of these various 
improvements is seen in the fact that many hard woods 
can be reduced to the conditions of an easy bleaching 
pulp in three and a half to four hours. Another instance 
of the value of modified conditions is to be seen in kraft 
papers. 

Kraft Paper.—The term “ kraft,’ meaning strength, has 
been applied to certain strong wrapping papers made by 
submitting wood to a modified soda process. The paper is 
remarkably tough, possesses a high tensile strength, and is 
a striking testimony to the possibilities of wood pulp as a 
material for making a great variety of papers. It is said 
that the process was discovered accidentally by a pulp 
manufacturer who, rather than waste some soda pulp which — 
had not been sufficiently digested, placed the half-boiled 
wood in an Edge runner or Kollergang, and reduced it to 
pulp by the simple process of friction. The paper finally 
obtained proved to be so firm and strong that the success 
of the new “ discovery ’’ was assured. 

The process, as usually carried out, involves the digestion 


CHEMICAL WOOD PULP 138 


of the wood in a soda or sulphate liquor containing about 
30 per cent. of the black lye from some previous cook. 
The wood is not completely boiled, but digested to a 
point’ at which the fibres can be disintegrated by simple 
friction. The undissolved ligno-cellulose acts as a useful 
cementing material, and the paper is bulky, light and 
strong. 

The success of the so-called “ kraft’’ papers made from 
soda pulp has led to the production of imitations, manufac- 
tured chiefly from sulphite pulps. The true kraft papers 
may be distinguished from the imitations by various 
differences in appearance and behaviour. The sulphite 
papers have a smooth, shiny surface when viewed in 
reflected light and held up on a level with the eyes, but this 
is only appreciated by a practised observer. The soda 
papers are tougher and capable of resisting a greater 
amount of friction, as may be proved by the well-known 
crumpling test. They can be twisted repeatedly without 
producing fracture, and this is a desirable feature in papers 
used for the manufacture of bags. The behaviour on tear- 
ing 1s generally different in the two papers, the soda being 
more resistant. 

The sulphite papers have a lower tensile strain, as a 
rule, than soda papers of equal weight, and also a lower 
_ percentage stretch or elongation under tension. 

These differences in physical qualities may be used as a 
means of discriminating between real and imitation kraft 
papers. 

It may further be noted that the natural self-colour of 
soda kraft papers is artificially imitated in the sulphite 
krafts by the use of yellow aniline dyes, which can be 


136 WOOD PULPeAN Delis Uske 


readily extracted by means of hot water, weak solutions of 
alkali, or rectified aleohol. The paper after treatment is 
quite another colour, and this in itself is evidence of a 
useful character. 

If small pieces of the paper are pulped and boiled in a 
solution of malachite green, the soda paper is dyed to a 
much darker colour than the sulphite. 

When the pulp is examined under the microscope, the 
pitted cells in the fibres of the soda pulp contain a little 
nucleus of green colour, which is easily detected. This 
test is not of much value, since many of the fibres even of 
the soda pulp do not show any strongly marked pitted 
vessels. 

Soda Recovery.—In the treatment of wood and other 
fibres by the soda process, at least 50 per cent. of the 
weight of raw material is dissolved, the yield of paper 
pulp being about 45—50 per cent. ‘The soluble soda 
compounds formed during the operation are rich in organic 
matter, and advantage is taken of this fact to recover the 
soda used. The black liquors discharged from the digestor 
are stored in tanks, together with much of the water used 
for washing the boiled pulp, and then concentrated by some 
system of evaporation. When the liquors are sufficiently 
concentrated, a thick pasty mass is obtained containing a 
large proportion of organic resinous matter, and this on 
being submitted to the action of a furnace catches fire and 
burns. The substance is thereby converted into a dry 
burning mass, and after the combustion is completed the 
resultant material consists mainly of impure carbonate 
of soda. : 

The whole process is one that calls for considerable skill 


CHEMICAL WOOD PULP 137 


and attention, particularly in the methods employed for 
utilising all the available heat. The cost of evaporation of 
the liquors and subsequent combustion of the black liquor 
is reduced to a minimum by a carefully regulated system of 
washing in order to prevent the accumulation of a large 
volume of weak washing waters, and by the utilisation of 
the waste heat obtained by the combustion of the organic 
soda compounds in the concentrated liquor. 

The following description of a modern recovery plant will 
afford some idea of the process. 

When the digestion of the wood or fibre is complete, the 
hot black lye is discharged from the digestors into storage 
tanks, which are usually fixed above the combustion 
chambers so as to maintain the temperature and prevent 
loss of heat. The fibrous material in the digestor is then 
washed with hot weak washings from some _ previous 
boiling, and lastly with hot clean water. The final 
washings only contain a small percentage of soda, and 
these are utilised as far as possible for a preliminary 
treatment of fibre from which the strong black lye has 
just been removed. The systems of washing vary in 
different mills, but the main object is the same in all 
cases, V1Z., a maximum recovery of the soluble soda com- 
pounds with a minimum volume of water. 

The evaporation of the black lye is effected by the use of 
a Porion furnace or a multiple-effect evaporator. 

The Porion Evaporator consists of a number of shallow 
pans built of brick, arranged in the form of an enclosed 
chamber, on the top of which are placed the tanks contain- 
ing the liquor to be treated. A furnace at one end supplies 
heat, which sets fire to the concentrated liquor in the 


138 WOOD PULP AND ITS USES 


adjacent pan, and the heat derived from the combustion of 
the thick lye is utilised in further evaporation of the liquor 
in the other pans and chambers. The Porion is in effect an 
evaporator and incinerator. | 

The Multiple - effect Evaporator is based upon the 
systematic utilisation of heat and reduction of pressure in 
the containing vessels, in series, so as to produce maximum 
vaporisation effect per thermal unit. The spent liquors are 
pumped through a series of tubes contained in several 
cylindrical vessels, the tubes of the first vessel being treated 
externally by steam at a pressure of 15—20 lbs. The 
liquor passing through the tube is raised to boiling point, 
and on being discharged into a separating chamber gives up 
the steam produced. The steam so liberated then becomes 
the heating agent for the series of tubes in the second 
cylindrical vessel, and the partly concentrated liquid falling 
to the bottom of the separating chamber is drawn by a 
vacuum through the tubes of the second vessel, which are 
therefore under reduced pressure. ‘The process is repeated 
through three or four systems of tubes, in each case the 
steam liberated in the separating chamber being used to 
produce a further concentration of the liquor. 

An apparatus of this kind will reduce 2,000 gallons of 
liquor per hour, having a specific gravity of 1:050 to 400 
gallons with specific gravity 1°250, evaporating off 1,600 
gallons of water per hour. 

The concentrated liquor leaving the evaporator is dis- 
charged into storage tanks and then allowed to flow continu- 
ously into a rotary furnace. The thick lye catches fire, 
burns with a steady flame, and is discharged as a black 
mass still burning, which is wheeled away, and allowed to 


CHEMICAL WOOD PULP 139 


char until the black carbonaceous matter has completely 
burnt off. 

Sulphate process.—First introduced by Dahl in 1883, for 
the treatment of straw, but now considerably applied to 
coniferous woods which do not soften under the soda treat- 
ment as the foliage of dicotyledenous woods. 

Sulphate of soda from which the process derives its name 
is of course inert, 7.e. without action upon the wood sub- 
stance and is added as a source of alkali, and to make good 
the mechanical losses in the process of recovery of the 
soda. 

This loss is approximately 10 per cent. From an 
analysis of sulphate liquor (see later) it is seen that there 
is a large proportion of sodium sulphide ; this is not added 
as such, but is formed by the reduction of the sulphate 
to sulphide in the process of recovery when the residue is 
ignited, this reduction being effected by the soluble organic 
matter in combination with soda. 

The sulphide has a hydrolysing action, similar in 
character to caustic soda, but has another function in 
that it has the effect of aiding the splitting of the lignone 
complex from the cellulose proper. ‘This dissociating 
characteristic is clearly seen when wood is treated with 
a mixture of sodium sulphide and hydrate, as against 
caustic alone of the same soda content. 

The general manufacture of sulphate pulp is restricted, 
for though the process yields an excellent pulp, yet the evil 
smelling compounds formed by the interaction of the 
sodium sulphide with the organic matter, limits its pro- 
duction to sparsely populated districts, as in Germany and 
Austria. 


140 WOOD PULP AND ITS USES 


ANALYSIS OF SULPHATE Liquor. 


Sodium sulphate. . 87 per cent. 
Caustic soda. : . 24 per cent. 
Sodium sulphide. . 28 per cent. 
Sodium carbonate . : . 8 to 10 per cent. 
Sodium acetate . 2 to 8 per cent. 


Soda and Sulphite Pulps.—Although at one time the 
woods employed for the production of sulphite pulps were 
almost exclusively pine and spruce, and the soda process 
was applied chiefly to poplar and dicotyledonous woods, the 
two processes are now used almost indiscriminately for any 
wood capable of yielding a paper-making fibre. 

It is exceedingly difficult to differentiate the processes by 
an examination of the chemical or microscopical character- 
istics of the fibres or the pulp, especially when the pulps 
have been bleached. There are certain broad distinctions 
between pure unbleached soda and unbleached sulphite 
pulps which can be readily noted, but these are not easily 
detected in papers containing a mixture of the two. 

It is impossible to state with any certainty that a 
bleached soda paper does not contain sulphite pulp, 
though any marked deviation from qualities expected in 
a soda paper would indicate the presence of sulphite pulp. 
If the soda pulp has been made from poplar wood, it is 
easily detected, and the admixture of any spruce may be 
approximately determined, but if the soda pulp has been 
made from spruce, no satisfactory analysis is possible. 

The differences between soda and sulphite pulps, even 
when prepared from the same type of wood, may be found 
in the physical qualities, since the soda pulp is of a light 


CHEMICAL WOOD PULP 141 


brown colour, soft and bulky, and very tenacious, while 
the sulphite pulp is reddish white, harsh, strong and 
less bulky. The presence of a much larger percentage 
of natural wood resin in sulphite pulp, namely, 0°5 per 
cent., as against 0°05 per cent. in soda pulp, can be used 
as the basis of a test, but it is of no value for sized 
papers. 

A small quantity of the pulp is heated continuously 
with carbon tetrachloride. The solution placed in a fresh 
test tube is mixed with an equal volume of acetic anhydride, 
cooled, and added to a few drops of concentrated sulphuric 
acid. With soda pulp no definite reaction occurs, but with 
sulphite pulp a pink coloration changing quickly to green 
is produced. 


Tort BLEACHING OF Woop PuLp. 


Two methods are in use for the bleaching of wood pulp, 
the most general being the employment of ordinary bleach- 
ing powder, and the secord being the treatment of the pulp 
by means of solutions of hypochlorite of soda or magnesia 
prepared by electrolysing the chlorides. This method of 
electrolytic bleaching is finding general favour amongst 
manufacturers when the power required can be supplied at 
a cheap rate. 

Bleaching with Chloride of Lime.—The general principle 
of bleaching wood pulp by means ofa clear solution of 
ordinary chloride of lime is simple and fundamentally a 
process of oxidation. ‘The method consists in immersion of 
the pulp in a given quantity of diluted bleach liquor of 
definite strength, but many modifications of method are 
available, and need to be closely studied in order to produce 


142 WOOD SRUEP FAN DST Ss Sisto 


the best results economically. The various systems in use 
may be briefly described. 

Bleaching in the Potcher. — This is the process most 
generally adopted by the paper-makers. The sheets of dry 
pulp are put into the potcher with water, broken up, and 
a definite volume of clear bleach liquor is added. The pulp 
is continuously circulated until the desired colour has been 
obtained, or until the bleach has been completely exhausted. 

When the operation is completed, the pulp is washed con- 
tinuously with fresh water, the exhausted bleach liquor and 
washings being removed in the usual way by means of the 
drum washer. In many cases the pulp is discharged into 
large tanks provided with perforated false bottoms and the 
washing process completed by draining. 

Bleaching in Drainers.— A modification of the above 
process which gives good results is frequently used. The 
pulp is broken up in the potcher, the requisite amount of 
bleach liquor is added and the contents of the potcher at 
once discharged into tanks where the bleaching process is 
allowed to proceed with the mass at rest. This method 
requires longer time, but gives excellent results in point of 
colour and economy of bleach. 

Bleaching by the Tower system.—FYor this process of con- 
tinuous bleaching a series of cylindrical vessels with taper- 
ing bases is used, about 16 to 20 feet high and 84 feet in 
diameter. 

The stuff is kept in circulation by means of a pump fitted 
at the junction of the tapering ends with an external pipe, 
the latter being so arranged that the circulating stuff can be 
pumped into the tower or to the adjacent one of the battery. 

Fitted in the upper part of the tower is a cone, arranged 


THE BLEACHING OF WOOD PULP 143 


centrally with, and almost touching, the sides of the outer 
cylinder to ensure thorough distribution of the stuff, as it 
is pumped up the external pipe (see lig. 19). 

It is usual in a modern battery of bleaching towers to 
pass the stuff as it comes up from the potcher through 
a concentrator in order to remove a large proportion of 
water whereby the bleaching is carried out more economic- 
ally and expeditiously. 

In series with the last bleaching tower also there is a 


Fic. 19.—Tower Bleaching Plant. 


This photograph on a reduced scale represents a plant capable of 
bleaching 10 tons of half stuff per diem. 


second concentrator, which removes the residual bleach 
liquor to a great extent, the necessary washing being 
reduced thereby to a minimum. 

This machine is very simple and compact, and capable 
of a large output. 

It is on this account to a certain extent replacing the 
more costly presse-pate system of purification. It consists 
of a revolving drum made with a central internal cone, so 
as to deliver water at both ends. The shell itself is of 
brass, drilled with holes and covered with a wire cloth. 
The stuff is pumped up through a butterfly throttle valve 


[dae WOOD PULP AND ITS USES 


into a splaying mouth, thus causing the pulp to flow along 
the whole width of the drum cover. 

The cover or hood is so arranged by means of packing, 
that the water in the half-stuff can be forced through the 
wire cloth of the revolving drum, by a pressure of 2 to 8 lbs. 
per square inch, leaving a mat of fibre upon it. 

The pulp is then picked off the wire by means of a 
jacketed couch roll, and a wooden doctor fitted to the latter 
serves to scrape off the fibre into boxes. An economy of 
about 25 per cent. in the bleach consumption over the 
ordinary method employed with a minimum of power is 
claimed by this system. The total time occupied in bleach- 
ing is usually about twelve hours without heat. 

Automatic Process. —In many wood pulp mills the 
‘“‘tower’”’ system is so contrived as to produce a con- 
tinuous automatic bleaching of the pulp. The pulp dis- 
charged from the digestors is thoroughly washed and then 
pumped into a series of large cylindrical vessels, so arranged 
that a continuous stream of pulp and water enters the first 
vessel together with a carefully regulated quantity of bleach 
liquor which also flows into the first tank at a constant rate. 
The mixture gravitates into the second vessel of the series, 
then into the third, and in this way throughall the vessels, 
until on reaching the last tank the bleach is fully exhausted 
and the pulp has attained the desired colour. The bleached 
pulp is then removed and thoroughly washed. 

Conditions for Economical Bleaching.—Ilt is difficult to 
accurately compare the methods adopted by paper-makers in 
bleaching wood pulp for the purpose of determining which 
system gives the best results, but there are certain conditions 
common to all methods. 


THE BLEACHING OF WOOD PULP 145 


In the first place, the bleaching powder must be of good 
quality, containing the specified percentage of available 
chlorine. The extraction of the soluble calcium hypo- 
chlorite also needs careful attention, as serious losses fre- 
quently occur when the powder is not properly exhausted. 

With chloride of lime containing 35 to 36 per cent. of 
available chlorine the quantity of clear bleach liquor 
obtainable for various densities is shown in table :— 


TABLE SHOWING THE NUMBER OF GALLONS OF BLEACH LIQUOR 
OBTAINED FROM 1 Owr. oF PowbER (34 TO 36 PER CENT. 
OF CHLORINE). 


i Een Tie tpes Vou ecticnat | 0s per conte powders [86 per ean, powder 
20 61:50 61:2 66:0 
19 58:40 65°3 69-0 
18 55°18 69-0 73-0 
07 52-27 13°5 17:0 
16 48°96 11-7 82:5 
15 45°70 84:0 88°25 
14 42°31 90-0 97°5 
13 39°11 98°3 104-2 
12 35°81 106-4 112°5 
ii 32°68 1165 120°5 
10 29-61 129-0 137:2 
9 26°62 142:0 151°5 
8 23°75 160°3 169°7 
7 20-44 186°1 197-2 
6 17°36 219°5 232-4 
5 14:47 264-0 278°6 
4 11:44 334-0 352°5 
3 8-48 448-2 475°5 
2 5°58 681-0 722°6 
1 2°71 1403-0 1488-0 
" 1:40 2725°0 2883°0 


Any deviation from the above figures may be traced to an 
unnecessarily prolonged agitation of the powder with water 
W.P. L 


146 WOOD PULP AND ITS USES 


or an imperfect washing of dregs. Fifteen minutes is 
sufficient to produce a liquor of maximum density with a 
residue which settles readily ; if the operation is continued, 
as it often is, for an hour or more, the insoluble residue 
becomes bulky and does not settle quickly. The result 
is that the first strong liquor cannot be so completely 
siphoned off from the residue. The best plan is to exhaust 
for fifteen minutes, allow the sediment to settle completely, 
siphon off as much as possible, and to agitate the residue 
for another fifteen minutes with fresh water, adding the 
weak liquor when clear to the first extract, so as to give 
a stock bleach liquor for use in the mill at a density of 
6° Tw. The dregs are again exhausted with water and 
the weak liquor so obtained utilised in exhausting the next 
batch of powder. 

It should also be noted that fresh liquors cannot be kept 
indefinitely in store tanks without deterioration. 

The unstable nature of solutions of bleaching powder, 
and the loss of available chlorine entailed when the liquor 
is not used under proper conditions, is well known to most 
paper-makers, although such depreciations in bleaching 
value are not always expressed in numerical terms. The 
following experiment will throw some light on the character 
and extent of the changes found in ordinary bleach liquor, 
when stored. 

Some fresh bleaching powder was taken, and a solution 
made by extraction with distilled water, having a strength 
of 7° Tw. Three samples of liquor were put aside under 
the following conditions :— 

A. Sample of clear liquor in stoppered bottle. 

B. Sample of liquor in an open vessel, and left exposed, 


THE BLEACHING OF WOOD PULP 147 


the crust of chalk which quickly formed on the surface 
being left undisturbed. 

C. Sample of liquor in an open vessel, agitated twice a 
day, at 9 a.m. and 4 p.m. 

These solutions were tested once a week, with a standard 
decinormal solution of arsenic. 


TABLE SHOWING C.C. oF ARSENIC SOLUTION REQUIRED BY 
1G¢.C. oF THE BuEacH LIQUOR. 


Period. topieral Open Eea Open vessel, 
bottle. not disturbed. agitated. 
At start . : : 7:05 7:05 7:05 
After 1st week : 6:90 6°90 3°90 
onde Awa. 6°85 6:60 0:40 
ae ort 6°8 4:0 0:27 
eros, 6°8 2°7 0-16 


In the case of the bleach liquor preserved in a bottle and 
kept away from contact with air, the loss of avaiiable 
chlorine is very slight. In the open vessel, where the 
formation of a crust has prevented continual contact with 
air, the reduction of strength is slight the first two weeks. 
Probably the rapid fall in the later weeks of the period 
may be due, in some measure, to the disturbance of the 
crust in removing samples for titration. In the case of the 
solution agitated each day the loss of strength is very rapid. 

The precise value of these changes are readily seen by 
reference to the accompanying tables, in which the losses 
are set out. 

L 2 


148 WOOD PULP AND ITS USES 


TABLE SHOWING AVAILABLE CHLORINE IN 100 C.C. OF 
THE BLEACH LIQUOR. 


A. B. C. 
Grammes. Grammes. Gramunes. 
| 
At start . F ; : 2 5() 2°50 2°50 
After 1 week . ; ; B45 2°45 1°38 
, Q2weeks. . . 2-43 2°34 0°14 
ae aes 2°40 0:96 0°05 


Expressing these results in a form more familiar to 
paper-makers—that is, in terms of the weight of normal 
bleaching powder—we get the following :— 


TABLE SHOWING THE AVAILABLE CHLORINE EXPRESSED AS LBS. 
OF NORMAL BLEACHING POWDER PER 100 GALLONS. 


A. B: C 

Lbs. Lbs Lbs 
At start . : ; 70°5 70°5 70°5 
After 1 week 69°0 69:0 39°0 
» 2 weeks : ; 68°5 66°0 4-0) 
Ne a 68°0 27°0 1°5 


The storage of the bleach liquor in the paper mill usually 
resembles the conditions of experiment B, and it will be 
noticed that the depreciation for the first week is very 
slight indeed. 


THE BLEACHING OF WOOD PULP 149 


The principal chemical change brought about by exposure 
to air is the disappearance of calcium hypochlorite and 
the increase in the percentage of calcium chloride, con- 
current with the formation of a considerable amount of 
chalk, more particularly with the sample agitated each 
day. 

Use of Residual Liquors.—The practice sometimes adopted 
of utilising residual liquors washed out of the potcher on 
the completion of a bleaching operation cannot be generally 
recommended. 

‘“‘ Back liquors ” may be reported as containing “ available 
chlorine” in useful quantity from the density as tested by 
the hydrometer, in conjunction with the occasional applica- 
tion of the usual chlorine test solution, viz., starch paste 
and potassium iodide. ‘The latter test, however, has no 
quantitative value, and the usefulness of the hydrometer as 
an indirect indicator of chemical strength depends upon the 
correct interpretation of density. Direct chemical tests are 
alone able to reveal the actual condition of the back 
liquors. | 

Circumstances under which residual liquors could be 
used with any advantage are to be found in mills where 
water is scarce. In such cases the pulp from boiling opera- 
tions might be treated with the residues for the purpose of 
using up any traces of bleach, and also economising washing 
waters. 

Composition of Residual Liquors.—The liquors left after 
the bleaching of wood pulp are of a complex composition, 
They contain soluble organic compounds, resinous matters. 
lime salts, residual hypochlorites and salts of higher 
oxides of chlorine (acids), ¢.g., chlorites and chlorates. 


150 WOOD PULP AND ITS USES 


Temperley gives the analysis of such a wood pulp liquor 
as follows :— 


Lbs. per 
1,000 gallons. 


Mineral residues, chiefly calcium chloride  126°6 
Organic residues, volatile on ignition ep) 


Total solids, dried at 100° C. . 188°6 


The surface scum obtained from the liquor had the 
following composition :— 


Lbs. per 
1,000 gallons. 
Resinous matter : : ; oo MOE 
Lime. : . . : : 4 ‘80 
Moisture . 3 ; ; . 8:90 
Fibre : : : : 2 .. 240 
Total ; ute 


The compounds in solution in residual liquors are very 
unstable, and react easily with the hypochlorite of fresh 
bleaching powder, so that the employment of washings in 
conjunction with raw bleach solution must result in a waste 
consumption of powder per ton of air-dry pulp. 

Temperley has shown this by some interesting experi- 
ments, and we quote these as illustrating an important 
factor in economical bleaching. Definite quantities of 
bleach solution were added to known volumes of ordinary 
water, and similarly to equal volumes of a carefally filtered 
residual liquor from the bleaching of a sulphite pulp. The 


THE BLEACHING OF WOOD PULP 151 


solutions were tested for a period of four hours at different 
temperatures, the results being very different in character. 


EXPERIMENTS WITH ORDINARY WATER. 


Bleaching powder used. 


Solution. Temperature Grains per Lbs. per 1,000 
used. gallon. gallons. 
Water 70° Fahr. 4°20 0°60 
AS OO mae 4°90 0°70 
120° _,, 9-10 1:30 


EXPERIMENTS witH ResipuaL Liquors. 


Bleaching powder used. 


Solution. Temperature Grains per Lbs. per 1,000 
used. gallon. gallons. 
Liquor 70° Fahr. 194-20 27°70 
“. SLU 248°50 35°50 
e IPA i 784:00 112°00 


The figures here show that residual liquors, even if 
colourless, are positively detrimental to efficient bleaching. 
Practical work demonstrates this, not only from the point 
of view of consumption, but, what is often of greater 
importance, from the point of view of colour. The same 
defect is found to a lesser degree in the use of unfiltered 
water, or water coloured by vegetable matter in solution. 

It is evident, therefore, that the practice of using residual 
liquors should be confined to their use for partial washing, 
and that they should not be used for diluting strong bleach 
liquors. 

There are many interesting and important details to be 
noted in connection with the bleaching of wood pulp. The 
process is frequently hastened by the use of live steam, 
which is blown into a mixture of pulp in the potcher. The 


152 WOOD PULP AND ITS USES 


rate of bleaching is thus considerably hastened, but the 
practice is not one that should be carried to an extreme. 
The economy of bleach is also controlled to some extent by 
the proportion of water to pulp. In some cases the number 
of pounds of air-dry pulp per gallon of liquid is much 
lower than it need be, and this usually tends to a greater 
consumption of bleach powder. The usual proportions 
are :— 


Air-dry wood pulp . : . 100 lbs. 
Amount of solution in potcher 160 gallons. 


The bleaching of very hard sulphite pulps not manu- 
factured originally for bleaching may frequently be assisted 
by slight modifications in the process. A refractory pulp 
may often be bleached to a good colour by the operation 
known as ‘‘ successive bleaching.” ‘The pulp is treated 
with a certain proportion of bleach liquor, which is then 
washed out and followed by a further quantity of fresh 
bleach liquor. This method is often sufficient to remove 
the yellow tinge found in half-stuff from poor qualities of 
pulp. 

Caustic soda may sometimes be used with advantage as a 
preliminary process in bleaching hard pulps which exhibit 
a reddish colour, but it is not economical to bleach “ low 
boiled” pulps, as the bleach consumption is too great, 
sometimes reading 30 per cent. [ven simple washing with 
hot water before bleaching gives a pulp of greatly improved 
colour. 

The improvements due to preliminary washing may be 
traced to the presence of soluble constituents, the nature 
of which is at present unknown. That these constituents 


THE BLEACHING OF WOOD PULP 153 


exercise a considerable influence on the bleaching may be 
seen from the following experiment :— 


PuLP BLEACHED FOR THREE Hours AT 70° FanrR. 


Conditions of bleaching. ip Seen eae oe Colour. 

Pulp bleached in the ordinar y mee 

ina shallow dish . 10°8 Moderate. 
Pulp bleached in the ordinary way in 

a bottle . : 10°8 PA 
Pulp bleached after ‘being first ex- 

tracted with water ; 12-0 Good. 
Pulp bleached after extraction with 

water followed by ether 76 Very good. 


The ‘time element” is an important factor in many 
mills owing to the lack of adequate bleaching plant, which 
in many cases can be attributed to the fact that the output 
of paper is increased by additional machines, but that this 
is not accompanied by the installation of further plant for 
the preliminary operations. Some pulps bleach quickly 
and readily, while others occupy a much longer time. It 
is not, of course, possible to determine whether a pulp will 
bleach easily by mere superficial observation; this can only 
deal with the associated characteristics of the pulps. The 
rate of bleach consumption is a close index of general 
bleaching quality, and the following experiment is of inte- 
rest as showing the differences between pulps which do not 
exhibit any great differences when simply judged on external 
characteristics :— 

Haperiment 1.—Brand C. An ordinary soda wood pulp. 
50 grammes air-dry pulp with 450 c.c. bleach liquor at 
65° Fahr. (containing bleach solution equivalent to 
11'7 grammes of dry bleaching powder). 


154 WOOD PULP AND ITS USES 


Experiment 2.—Brand B, <A sulphite pulp. About 14 
per cent. of bleaching powder, calculated on the air-dry 
weight of pulp, added. Actual consumption for colour 
required amounted to 12°5 per cent. 

EKaperiment 38.—Brand A. A sulphite wood of good 
colour, requiring a consumption of 8 per cent. of 
bleach. 

Setting out in tabular form the rate at which the amount 
of dry bleaching powder is consumed, the following results 
are obtained, expressed in terms of the percentage rate. 
The total bleach added is taken as 100, and the proportions 
consumed each hour are taken as percentages of the total :— 


RATE OF CONSUMPTION. 


Hours. Brand C. Brand B. Brand A. 
0 0 0 0 
1 33°0) — 20°0 
2 44°0 30°0 33°0 
3 d1°0 — 43°0 
a 66°0 00°0 49°0 
5) 70:0 — 56°0 
6 — 78:0 63°0 
i $0°0 90°0 70°0 


| 


It will be noticed that in none of these cases was the 
total bleach consumed in the seven hours. If the figures 
are plotted out on a curve, the differences in behaviour 
become very clear and may be expressed in definite form. 

Thus, with Brand C the pulp bleaches very rapidly 
during the first hour, and then bleaches at a uniform rate 
for the succeeding four hours, and subsequently consumes 
bleach very slowly. 

In the case of Brand B, the pulp bleaches somewhat 


THE BLEACHING OF WOOD PULP 155 


rapidly during the first hour, and then the rate of con- 
sumption is quite uniform for the following six hours. 

Finally, with Brand A the pulp, in common with most 
brands, consumes bleach rapidly at first, but afterwards 
the rate of consumption gets slower and slower. 

These three brands are typical of the conditions which 
will occur with the majority of pulps. The rate of con- 
sumption beyond the period of seven hours is not of 
immediate interest to the paper-maker, but it is still a 
question of some moment in an investigation of this kind. 

Owing to the great differences between pulps as to their 
bleaching qualities, it is important to have methods for 
determining the amount of bleach consumed in bringing 
the pulp to any desired colour. The following methods 
may be adopted :— 

The Approximate Method of Determining the Consumption 
of Bleach.—The behaviour of the pulp when brought into 
contact with bleach solution can be studied by paper- 
makers to some extent without special appliances or chemi- 
cals, provided they possess some fairly sensitive balance 
and a few measuring vessels. The following rough-and- 
ready method may be adopted with advantage in many 
circumstances, although the results are only approximate, 
and cannot be accepted as correct enough for purposes of 
settling any disputes :— 

Take 200 grammes of the pulp and wet out in warm 
water; place in a large bottle with a further quantity of 
water; add a few beads or, better, garnets, and shake 
vigorously. Most pulps can be broken up sufficiently for the 
laboratory test in this way. Strain off in a sieve, squeeze 
out excess of water, and divide the moist mass into a number 


156 WOOD PULP AND ITS USES 


of equal parts, ¢e.g., 10 portions, so that each lot represents 
20 grammes of the original air-dry pulp. Pulps which will 
not break up easily by this method are reduced with pestle 
and mortar to the required condition of complete disin- 
tegration. Unless the pulp is thoroughly broken up, the 
mass bleaches unevenly and does not give uniform results. 

Now to each portion, in a convenient open vessel, add 
200 c.c. water and varying quantities of clear bleach liquor 
from mill stock, so as to obtain a series of bleaching tests. 
If the mill stock of liquor stands 6° Tw., then it is 
sufficient to take the following data :— 

1 gallon of 6° liquor = 3 |b. of good bleaching powder. 

1,000 c.c. of 6° liquor = 50 grammes of good bleaching 
powder; 1 c¢.c. = 050 grm. 

From this assumption it is possible to work out the 
several quantities of liquor required in the experiment 
suggested. 

The following table shows the necessary volumes of 
liquor for certain percentages of dry powder :— 


Volume of bleach 


No! ‘| caiavy pulp ih | bleaching powder |. i dry powdor ai Sauer bs eupiee 
mixture. to be added. required, See tatei aa 
1 20°0 2°0 0-4 grms. 8°0 c.c. 
2 20°0 4°0 O'S ss LGsae. 
3 20°0 6°0 1-20) oS 24°07) ,, 
4 20:0 8:0 ros. Spell = 
9) 20°0 10°0 2-00 Ga 40°0 ,, 
6 20:0 12°0 2AOs 48°0 ,, 
7 20°0 14°0 satel Oh ae 06°07 8 
8 20:0 16°0 aie A0 Eos 64:0 ,, 
g 20°0 18°0 3005 ae: 12/0 ye 
10 20°0 20-0 4:00 Ses SO gee 


THE BLEACHING OF WOOD PULP 157 


If all these mixtures are started simultaneously, it is 
only necessary to stir them occasionally and to note the 
time at which the bleach liquor in each becomes exhausted. 
The time of exhaustion is determined by means of starch 
and iodide test papers, which give a blue coloration as 
long as the mixture contains any available chlorine. The 
observer will then add another column to the above table, 
setting out the various periods of exhaustion. 

This experiment not only serves to bring out clearly the 
rate of consumption, but also gives information as to the 
amount of bleach required to produce a certain result in 
reference to colour. For example, the colour gradually 
improves from test No. 1 up the scale towards No. 10. 

In the case of a pulp which requires about 16 per cent. 
of dry bleach, the changes in colour between tests numbered 
7 and 8 will be very slight. Test No. 8 may represent a 
maximum of colour with a certain percentage of bleach, 
which maximum it may not be necessary to reach for the 
particular paper being manufactured. This is a matter for 
the paper-maker to decide. 

Standard Method.—A more accurate method of deter- 
mining the amount of bleach required for pulp, and one 
which might be acceptable as a standard official method, is 
given in the form of instructions as follows :— 

Selection of Samples from Bulk.—From the bales of pulp 
delivered into the mill select 2 per cent. of the number of 
bales. From each of the selected bales remove one sheet. 
The sheets so obtained should then be divided into two 
portions, one of which is to be retained for purposes of 
reference and the other portion utilised for the laboratory 
test. 


158 WOOD PULP MAND SI is. USS 


Cut small strips 


Selection of Laboratory Test Suniples. 
1 inch wide, and any convenient length of 2 or 3 inches 
from each of the sheets in the bulk samples, sufficient to 
give three or four lots of about 10 grammes each. 

Preparation of Bleach Liquor.—Make up a bleach solu- 
tion containing 40 grammes of good powder per 1,000 c.c. 
This gives a 4 per cent. (vol.) solution, which is a convenient 
working strength. If 40 grammes of good bleaching 
powder are thoroughly mixed with water and filtered, the 
residue being properly washed and the filtrate made up to 
1,000 ¢.c., the final solution is of such a strength that 
4 c.c. of standard arsenic solution is equal to 1 c.c. of the 
clear bleach liquor. ‘This figure will vary according 
to the quality of the powder and the completeness of the 
washing of the powder. The solution should be carefully 
standardised with decinormal solution of arsenic, so that 
the percentage of available chlorine is known, and the exact 
number of ¢.c. giving 1 gramme of 35°5 per cent. bleaching 
powder, calculated. The convenience of making up the 
solution in this way is obvious. If we assume a good 
bleaching powder as one containing 35°5 per cent. available 
chlorine, then 


, (00355 grm. Cl. or 
1 c.c. standard arsenic = ; -01 erm. bleaching 
( powder. 


25 ¢.c. bleach solution = 1:0 grm. bleaching powder. 


Preparation of Test Sample.—Weigh out exactly 10 
orammes of the pulp from the selected test sample, macerate 
and beat in a mortar with successive small quantities of 
water, using for this purpose 50 ¢.c. Place the mixture in 


THE BLEACHING OF WOOD PULP 159 


a beaker, standing this in a water bath, by means of which 
the mixture can be heated. 

The object of using a measured quantity of water, 50— 
60 ¢.c., is to ensure that the final mixture of pulp and bleach 
contains a definite proportion of solution to the amount of 
dry pulp taken for the experiment, reasons for which have 
already been discussed. 

Bleaching.—Add 62°5 c.c. of bleach liquor to the contents 
of the tumbler, stir with a glass rod, and add 47—50 c.c. of 
water. 

The proportion of solution to air-dry pulp varies con- 
siderably in different mills. The average of figures which 
have been placed at the disposal of the writer would 
indicate that the following proportions might be utilised for 
purposes of experiment :—10 grammes of air-dry pulp and 
160 ¢.c. of solution. With regard to the amount of bleach 
liquor used, experience would suggest taking an excess of 
bleach liquor and determining the bleach unconsumed in 
the solution. Most pulps can be treated by adding bleach 
liquor obtained from good bleaching powder equivalent to 
25 per cent. of the weight of wood pulp taken for experi- 
ment. In the above case 62°5 c.c. of a good bleaching 
solution would be equivalent to 2°5 grammes of powder. 
This figure, as already explained, will vary slightly, but as 
the value of the solution is determined by means of standard 
arsenic, the variations can be easily allowed for. 

Temperature, etc.—Maintain the water bath at a tempera- 
ture of 100° Fahr., stirring the mixture occasionally with a 
glass rod, and testing the solution from time to time with 
starch iodide paper. When the colour reaches the required 
standard, filter off the solution and wash the pulp. 


160 WOOD PULP AND ITS USES 


A filter paper is not necessary for the purpose of sepa- 
rating the solution, because the pulp, when thrown into a 
funnel, acts as its own filter. The washing should be 
continued until the filtrate shows no coloration with starch 
iodide paper. 

Titration of Filtrate.—The amount of unconsumed bleach 
in the filtrate is determined by means of standard arsenic, 
and thus the amount of bleach actually consumed by the 
10 grammes of pulp accurately determined. The amount 
of powder used for the bleaching of the pulp is then a 
matter of calculation. 

Checking the Result.—If the amount of bleach originally 
added proves to be much in excess of that actually consumed, 
carry out a second test, using bleach liquor containing a 
slight excess above the equivalent of bleaching powder 
shown by the first experiment. 

In all experiments of this kind it is advisable simply to 
use only a slight excess of powder, and if the appearance of 
the wood pulp gives some clue as to the probable amount 
of bleach, the first experiment will frequently give the 
desired result without a check test. 

Sample Sheets of Bleached Pulp.—By means of a small 
hand mould make up a few sheets from the bleached pulp, 
in order to have a permanent record of the colour produced 
under the conditions of the experiment. Attach these 
sheets together with one or two pieces of the original pulp 
to the certificate. 

Recording the Colour of Pulp.—It sometimes happens that 
with a series of pulps bleached under similar conditions the 
sheets vary but little in colour. Such small differences 
point to the necessity of a method of recording colour 


THE BLEACHING OF WOOD PULP 161 


more correct than comparative verbal descriptions. Exact 
records are those of colour analysis by means of the Tinto- 
meter. The following experiment may be quoted as an 
example :— 

Three varieties of sulphite pulp were examined, and small 
sheets were made up from the three samples as follows :— 

(1) Sheets of the original unbleached pulp. 

(2) Sheets from the pulp. after being bleached with 10 

per cent. of bleaching powder. 

(3) Sheets of the pulp after treatment with 18 per cent. 

of the powder. 

The colour analysis of the samples is given in a table. 

These results are interesting and instructive, as showing 
the gradual elimination of the non-cellulose constituents of 
the pulp and the exact changes in colour due to the varying 
extent of bleaching or oxidising action. The stages of colour 
are represented by the combinations of the standard glasses 
used. In the original pulp we have the combinations of 
red, yellow and blue; in the pulp bleached with 10 per 
cent., red and yellow only, and in the final product some 
traces of yellow. This table (see next page) is the more 
interesting because the gradual elimination of the colouring 
matter 1s expressed in numerical terms. 

The significance of the colour readings is naturally 
only familiar to those who are constantly handling the 
Tintometer instrument. When an observer has become 
accustomed to the depth of colour of the various standard 
classes, then the numerical expression conveys an accurate 
idea of the colour, so that after some practice he obtains a 
mental picture of the colour of the pulp from the figures 
which record the visual colour. 

W.P. M 


162 WOOD PULP AND-ITS USES 


2 E Standard glasses | 
oe used. | 
Substances examined. = = Visual colour. 
= | Red. | Yellow.| Blue. | 
os | 
| 
Original pulp-— Black. | Orange. | Yellow. 
ramplel . 16) al 6 5-985 6 a we 1G "84 05 - 
ee Lee. 1-394 1:4 sian, sec ‘60 Sat 
| Red. 
*) SB co Meee 1°55] 1°5 “997 390 "00 7 ee Uo 
Pulp bleached 
with 10 per | 
cent.— | Orange. Yellow. 
Sample 1. “L260 Ly "43 
a Zim LON 100 15 =|) *48 
. ote ‘O60 1050 "26 | :44 
Pulp bleached 
with 18 per 
cent.— | Green. | Yellow. 
Sample 1. "20 fee laa Od "25 
5 2 iat “30 30 
‘3 Sak ioe "32 


Electrolytic Bleaching. 


This term, in its stricter and more correct sense, implies 
a process in which a bleach liquor prepared by electrolytic 
methods, is used as a substitute for the calcium hypochlorite 
solution obtained by treating ordinary bleaching powder 
with water. In practice this resolves itself into the use 
of a sodium hypochlorite solution prepared direct from 
common salt by electrolysis. 

In a wider sense the term may also be applied to the use 
of bleaching powder which has been manufactured from 


THE BLEACHING OF WOOD PULP 163 


chlorine obtained electrically from salt. In this case the 


3:9 


process is only an indirect ‘‘ electrolytic bleaching,” since 
the actual bleaching agent is still ordinary chloride of lime. 

In their relation to the bleaching of wood pulp both 
systems need to be considered, since there miglit be certain 
advantages with the indirect electrolytic treatment in 
factories favourably situated. 

In the first system a solution of common salt is submitted 
to the action of an electric current, which decomposes the 
sodium chloride and ultimately produces two substances, 
caustic soda and chlorine. These products interact in the 
solution to form sodium hypochlorite, which is then at 
once available for bleaching. Only a small proportion of 
the salt is actually converted into the active hypochlorite, 
and the process depends for its commercial success on a 
supply of cheap salt and electrical power. 

In the second system a solution of common salt is also 
submitted to electrolysis, but the resultant products of 
decomposition are carefully separated, and not allowed to 
combine. The caustic soda is drawn off continuously and 
subsequently concentrated, while the chlorine gas is taken 
off and brought into contact with dry lime for the manu- 
facture of bleaching powder, or passed at once into milk of 
lime and thus converted direct into bleach solution. Com- 
plete decomposition of the original salt is effected by this 
means, and two products of commercial value are obtained. 
In pulp factories where wood is treated by the so.!a process 
the use of this second system might be a decided advantage. 

The process of electrolysis presents no difficulties in the 
laboratory, but the practical application of them for the 
purpose of devising a commercial and remunerative system 

M 2 


164 WOOD PULP AND ITS USES 


for the manufacture of alkali and chlorine has proved a 
difficult and costly task. 

The laws of electrolysis, together with the terms and 
nomenclature expressing the relations of current to chemical 
work, are mainly due to Faraday. In regard to the electro- 
lysis of common salt a current of one ampere passing 
through a solution of the sodium chloride will liberate 
1°32 grammes of chlorine per hour and the equivalent 
quantity of caustic soda simultaneously. 

The terms usually employed in reactions relating to 
electrolysis are as follows: 

Ampere.—The unit of current or rate of flow in terms of 
coulombs per second (tnfia). 

Volt—The unit of electromotive force, or electrical 
pressure, which applied to a conductor having a resistance 
of one ohm, will give a current of one ampere. 

Ohm.—The unit of resistance, which is that of a uniform 
column of mercury 106°3 cm. long, and mass equal to 
14°45 grms. 

Coulomb.—The unit of quantity, or the quantity of 
electricity derived from a current of one ampere in one 
second. 

Watt.—The unit of power is the power of a current of 
one ampere flowing under a pressure of one volt. It is_ 
equal to one joule per second. 

Joule.—The unit of work, or the energy expended in one 
second by a current of one ampere passing through a 
resistance of one ohm. 

Electrolysis—The chemical change of decomposition 
produced by a current of electricity passing through a 
solution of a substance. 


THE BLEACHING OF WOOD PULP 165 


Electrolyte-—A term applied to the solution undergoing 
electrolysis. 

Electrode.—The terminal conductor, usually carbon or a 
metal, by means of which the current is passed into or 
taken away from the solution undergoing electrolysis. 

Anode.—The conductor or electrode which conducts the 
current into the solution or electrolyte. 

Cathode.—The conductor or electrode which conducts the 
current out of the solution or electrolyte. 

Anion.—The product of electrolysis obtained from the 
electrolyte which is given off at the anode, and is always 
electro-negative in character. 

Cation.—The product of electrolysis obtained from the 
electrolyte which is given off at the cathode, and is always 
electro-positive 1n character. 

Power Consumption.—This is usually measured in “ kilo- 
watts.” 

A watt = ampere X volt. 
A kilowatt = 1,000 (amperes xX volts). 
746 watts = 1 horse-power. 


Production of active chlorine.——-The equivalent of one 
ampere passing through a solution of salt is 1°32 grammes 
of chlorine per hour (at the anode). In practice a smaller 
yield is obtained owing to secondary reactions and equiva- 
lent loss of current efficiency, increasing as the amount of 
‘active chlorine” accumulates. The actual mean produc- 
tion is about one gramme of chlorine per ampere-hour for 
weak liquors. On this basis with a potential of 8°5 volts, 
For 1 gramme chlorine = 1 ampere-hour. 

1 kilo chlorine = 1,000 ampere-hours. 
1016 kilos chlorine = (1,000 x 1,016 xX 3°5) watts. 


166 WOOD PULP AND ITS USES 


or 1 ton chlorine = 8,556,000 watts. 
= 3,556 kilowatts. 

The actual consumption of power under the systems now 
in practical use appears to be 5,000 kilowatts for a ton of 
‘“‘ active chlorine.” 

The earliest attempts at the direct industrial production 
of bleach liquor, ¢.e. a solution of a hypochlorite, were made 
by IX. Hermite over twenty years ago. On this system the 
electrolyte was a solution of Magnesium Chloride (2—8 
per cent. MgCly), which was electrolysed to a concentra- 
tion of about 38 grammes “ chlorine ”’ per litre. 

An essential feature of this process was the continuous 
circulation of the electrolysed liquor as between the electro- 
lyser and the beating engine, and the realisation of the 
cycle of changes, viz :—the electrolysis of the magnesium 
chloride to hypochlorite in the electrolyser and its reversal 
in the beating engine as the result of chemical work done. 
The Hermite system on this principle was found unwork- 
able, for, owing to secondary reactions and waste consump- 
tion of bleaching compounds, the percentage current 
efficiency was very low. It is still used, however, as a 
method of producing a hypochlorite solution. 

There are now several types of electrolytic apparatus in 
use, based on the conversion of salt (sodium chloride) into 
sodium hypochlorite. 

Haas and Oecitel Apparatus.—This electrolyser is simple 
in construction and working, and is in considerable favour 
where small quantities of bleach liquor are required, 
particularly in laundries and textile works. It consists of 
a& narrow earthenware vessel containing the electrodes, 
which are so arranged that the vessel is divided into a 


THE BLEACHING OF WOOD PULP. 167 


number of separate compartments, provided with a feed 
pipe to each near the bottom, and an overflow channel at 
the top. This vessel is immersed in the large store tank 
containing a salt solution of 10° Be. When the current 
passes, the hydrogen gas liberated at the cathode causes 
the solution to froth and rise up in each compartment. 
This produces an automatic continuous circulation of the 


Fic. 20.—Haas and Oettel Electrolyser. 


electrolyte solution, since the expulsion of some of the 
latter through the overflow pipes produces a partial vacuum 
in each chamber, which causes fresh liquor to pass into the 
chambers through the feed pipes at the bottom. 

Adequate arrangements of cooling pipes ensure a com- 
paratively low temperature in the cell, which is essential to 
the production of a maximum amount of hypochlorite and 
a minimum amount of chlorate. 


168 WOOD PULP AND. ITS USES 


The current is maintained until the desired strength of 
‘‘active chlorine”? has been obtained, at which point the 
charge is drawn off into store tanks, and a fresh quantity 
of salt pumped into the apparatus. The process is 
therefore intermittent. 

The standard pattern for the production of large 
quantities of sodium hypochlorite as required in the paper- 
mill is shown in Fig. 20. 

It is constructed wholly of stoneware, the electrodes are 
made of “ carbon,” and the apparatus is adapted for a con- 
tinuous current at 110 volts. The makers quote the follow- 
ing figures as indicating its output and economy of working, 
based on a 12 hours test :— 


Capacity of Tank 750 litres = 166 gallons. 

Salt used. 280 lbs. = 166 gallons at 23° Tw. 
Temperature of solution 20° C. 

Current 43 amperes. 

Potential 110 volts. 

Chlorine obtained 26°73 lbs. 


With these results the figures for the production of one 
ton of active chlorine are :-— 
One cell produces in one working day 53:0 lbs. chlorine. 
110 x 48 x 24 

1,000 
One ton chlorine requires power = 4,800 kilowatt hours. 
and salt = 10°5 tons. 

Siemens and Halske Idlectrolyser.—This apparatus is 

already in use in several paper-mills, notably the Borregaard 


= 113°6 kilowatt hours. 


Power required 


works of the Kellner - Partington Co. in Norway. The 
electrodes are made of platinum-iridium gauze arranged 
horizontally in shallow stoneware electrolysers, or in 


THE BLEACHING OF WOOD PULP 169 


CHLORINE CAUSTIC SODA CELL 


———— SECTION 


ER DO DS ARORA IDOE AS EBLE EEL IOI OOS 
FI IAT OILY IEF AI LAPLAND CD DPN NT BIT ITV AD OT 
cs 


CARBON ANODE HEATING PIPE 
IRON WIRE NET, CATHODE 


ANODE CHAMBER. 
CONCRETE COVER. CATHODE CHAMBER 
CHLORINE OUTLET CAUSTIG SODA OUTLET. 


DIAPHRAM CLOTH. SALT INLET 
IRON BATH HYDROGEN OUTLET 


Greg 21. 
iron vessels suitably lined with glass or other insulating 
material. These vessels are so constructed as to form a 
series of small independent decomposing cells, and the 


170 WOOD PULP AND ITS USES 


solution of salt is passed continuously through the whole 
series. ‘The electrodes are connected up so that no 
electrical connections inside the several electrolysers are 
necessary. The bleaching liquor produced is drawn off 
into reservoirs, or kept in circulation until the ‘‘ active 
chlorine” is at the working strength. 

The makers’ of this apparatus have published interesting 
statistics from time to time and give the following 
particulars in reference to some works in Switzerland. 

At this mill the quantity of bleach liquor obtained in 12 
hours amounts to 2,800 litres containing 15 grammes of 
active chlorine per litre. 

Current used = 120 amperes at 120 volts. 

Salt consumed = 250 kilos in 2,800 litres of water 
to give 15 grammes chlorine per 
litre. 

Working out the cost of production with the above figures 
the results are :— 


: : 2 O00 Rel Oe ete 
Chlorine produced ier = 34 5 kilos. 
; 120 1D, r 
Electrical power = a0 Le = 173 k.w. hours. 
Electrical power for 1,016 kilos i 73e<aOle 
‘ = k.w. hours. 
chlorine at 34°5 


Klectrical power for 1 ton chlorine = 5,090 k.w. hours. 


Salt for 34°5 kilos chlorine = 250 kilos. 
» >», 4,016 kilos chlorine = 7,500 kilos. 
9 ”9 1 ton chlorine aL salt. 


1 « Papermaker’s Monthly Journal,’ May, 1910. 


THE BLEACHING OF WOOD PULP 1g)! 


The following table has been given to show the cost of 
power and salt for one kilogram active Chlorine. 


Cost of power Cost of salt Cost of power 
No. Price per litre. for 1 kg. active for 1 kg. active and salt for 1 kg. 
chlorine. chlorine, active chlorine. 
Sa GE d, d. d. 
1 1 4 1°42 0°72 2°14 
phe Mis 2°85 0°72 ood 
1) aL a7 0°72 6°42 
2 1 4 15 0'S64 2°164 
lez 2°6 0°S64 3°464 
We a°2 O-S64 6:064 
5) 1 4 1-2 1:08 2°28 
1 2 2°4 1:08 3°48 
ite a 4°8 1:08 ass 
4 1 4 1165 1-44 2°09 
I 2 2°30 1-44 oi4 
as eal 4°60 1°44 6°04 


The Siemens and Halske apparatus is so constructed that 
the products of electrolysis, namely chlorine gas and caustic 
soda, can be separated continuously during electrolysis, and 
when so desired caused to interact outside the electrolyser 
for the production of bleach liquor direct. The makers 
claim that by this means the same amount of active chlorine 
can be produced with lesser power and with a smaller pro- 
portion of salt, and state that the power consumption is 3°5 
to 4 k.w. hours for each one pound of active chlorine. It 
is obvious that a plant capable of producing bleach and soda 
in this way possesses many advantages over those forms of 
apparatus in which only bleach lquor is produced. In 
localities where lime is plentiful and cheap, and where 
caustic soda finds a ready market, the Siemens and Halske 
electrolyser should give economical results. Taking the 
figures above quoted with the apparatus utilised only for 


172 WOOD PULP AND ITS USES 


the manufacture of bleach liquor, the cost of one ton of 
active chlorine would appear to be as follows :— 


Quantities. Price. Total. 
£ Seg) Soke. | 

Power . : . |5,090 k.w. hours | at ¢d. per unit! Ose) 

Salt : d ; 7°5 tons at 12s. ASLO 

Renewals : : = say Oc 0a 
Interest and other 

charges. —-- say bre Oee0 

<1 1 Game 


1 The unit is a kilowatt hour. 

Schuckert's Electrolyser.—This apparatus consists of cells 
similar to those employed in other electrolysers, the chief 
feature being the special form of the electrodes. In the 
Siemens and Halske apparatus the electrodes are con- 
structed of platinum and iridium, while in the Haas and 
Oettel they are provided with electrodes made entirely of 
eraphite. In Schuckert’s electrolysers the positive electrodes 
are made of platinum and the negative electrodes of graphite. 
This arrangement 1s based upon the fact that the carbon 
electrode is not attacked by the electro-positive element 
at the negative pole, and the platinum is not acted upon by 
the electro-negative compounds present at the positive pole. 
Several advantages are claimed for this arrangement, as not 
only does the apparatus require less frequent renewels, but 
the presence of smaller particles of carbon in the liquid is 
avoided. ‘This electrolyser appears to be capable of provid- 
ing strong solutions of bleaching liquid. With a 10 per cent. 
solution of salt a bleaching liquid containing 15 grammes of 


THE BLEACHING OF WOOD PULP 173 


active chlorine per litre can be obtained with an energy 
consumption of 3°2 kilowatt hours and a supply of 5:4 Ibs. 
of salt per lb. of chlorine. The usual limit is 20 to 22 
erammes of active chlorine to the litre, and with a Schuckert 
electrolyser 30 to 85 grammes per litre can be obtained. 

Some interesting experiments have been made bv Dr. 
Fraass with electrolytic bleach liquor prepared by the 
Schuckert apparatus.t 

The cellulose examined was easy bleaching sulphite pulp. 
A weighed quantity of the pulp was mixed with water and 
a definite proportion of bleach liquor (a) from chloride of 
lime and (b) from electrolytic bleach liquor. The 
temperature of the operation was maintained at about 80° C. 
until the whole of the chlorine had been consumed. The 
results of this test are given as follows :— 


CoMPARISON OF BLEACHING EFFECTS OF (a) CHLORIDE OF LIME 
AND (6b) ELecTRoLyTiIc LYE. 


Pulp Active chlorine | Chlorine used 


fe Osco I crtames pea | eramnionat Resulting white, 
: litre. air-dried pulp. 
a b a b 
1 Lela 0°67 | 0°67 | 2°00 | 2°00 | Same with both. 
Za 20 1°25 | 1:25 | 1:99 | 1-99 | Better with electrolytic lye. 
3 1312;7 | 0°80 7-0°80 |-2-00 / 2°00 fe 
+ ae OO eUs ORO bd Lalo? Aeles2 a 
5) Deli? a 0-50 0780 2°02- |) 2°02 is 
6 deste OU ymeO 60 Yee 0042-00 ie 
teeta 27) 80-79-0079 122-00 |) 2-00 if | 
8 1:20 LOO e100 5 2-00 e) 2°00 - 
9 1220 150° 1-50 1.3°00:}, 3°00 Fie | 
10 i120 TOO A004 200-6200 
Tt le20 L009 2:00 4) 72"00 +1 2°00 3 
12 hea) 1°50 | 1°50 | 3°00 | 3°00 e 


' For further details see ‘‘ Papier Fabrikant,” 1909. 


174 WOOD PULP AND ITS USES 


Further experiments were made by Dr. Fraass to deter- 
mine the actual saving of chlorine, if any, effected by the use 
of electrolytic chlorine. The following results were obtained. 


(a) REFERS To CHLORIDE OF LIME; (b) REFERS TO 
ELECTROLYTIC LYE. 


elt) Bal el Se ae Lge 
No. Sora ee Grarees per Pr ence of jin per cent. Better white with. 
litre. air-dried pulp. | Chlorine. 
a b a b 

14 Pa 1:0 150995 ie 202m 199 1°45 b. 

16 1; 20 3°00, | 2°99 0°90 | 5°40 1:90 b. 

18 L218 AZT ade 23 2°06 | 2°00 2°90 b, 

20 1:16 1°29 | 1°24 2 UGG 1299 3°40 b. 

22 1320 2°24 Wee 4°54 | 4°34 4°40) b, 

24 20 2°27 | 2°15 | 4°54 | 4°30 5°26 | aand b same. 
26 1:12°5 | 0°89 | 0°80 2°21 | 2°00 10-0 a. 

28 1F220 1:00 | 0°90 2:00 | 1°80 10°0 a, 

30 Let 2F 0 SO gO re. 2:00 | 1°80 10°0 a. 


From the foregoing brief account of electrolytic bleach- 
ing systems it would appear that evolution on the basis of 
experience has limited these systems to the production of a 
solution of a hypochlorite which is used upon the pulp or 
cellulose textile to be bleached, and is then rejected as a 
waste liquor after the bleaching agents are exhausted in 
doing chemical work upon the pulp or fabric. 

The idea of an industrial cycle as advanced by Hermite 
is rendered impossible by the fact, which is too often over- 
looked, that with the bleaching or oxidising action there are 
secondary reactions, as a result of which organic products 
pass into solution. These products will consume oxygen 
until reduced to compounds of the lowest molecular weight. 
This of course is entirely waste work. 


THE BLEACHING OF WOOD PULP 175 


The electrolytic systems finally evolved are therefore 
intermittent, and the rejection of the waste solution involves 
a loss of so much salt which is too dilute a form to be use- 
fully recovered. 

When we come to the question of the direct production 
of caustic soda and chlorine, we arrive in the region of 
“heavy” chemical industry. 

As a result of inventive evolution there are two systems 
finally established in this country, which are those of 
Castner-Kellner, and Hargreaves-Bird. 

Each of these systems produces chlorine as such, which 
is converted into bleaching powder, or bleaching liquor, as 
an ordinary chemical operation outside the electrolytic 
system. 

As regards the work of the cathode, or soda end of the 
process, the Castner-Kellner system produces caustic soda 
owing to the special disposition of its electrode, whilst in the 
Hargreaves-Bird process the soda which is produced as 
caustic soda is removed in the form of carbonate. 

These well-established systems, for the production of 
alkali and “ bleach,” are not easily engineered, and they 
are in many respects unsuitable for small production. 

The matter with its technical and commercial issues is 
much too complicated to be usefully discussed within the 
scope of this work. 

Many problems are presented which are as yet by no 
means solved and it is quite possible that the over-pro- 
duction of chlorine, which is an incidental feature of these 
systems, may lead to further developments of the industrial 
production of cellulose on very different lines from those 
which are exploited to-day as almost stereotyped. 


176 


Imports oF Woop PULP INTO GREAT BRITAIN, 


WOOD PULP AND ITS USES 


1904—1908. 


(From the Annual Statement of Trade of the United Kingdom). 


QUANTITIES. 
1904. 1905. 1946. 1907 1908. 
oes Dry. Tons. Tons. Tons, fons. Tons. 
I’rom Russia -| 9,033} 12,179 | 11,698) 13,558 7> 157501 
» sweden . 131,655 |133,564 |127,046 |157,916 |163,074 
NOT wa ya 09,213 | 63,948 | 77,047 | 70,957 | 77,665 
, Germany 5,609 | 7,186| 7,584 | 15,514 | 23,687 
,, Netherlands 2,131 | 2,622] 25595 | 3; 280 seme 
,, Portugal 2,115} 2;482°) "(2,219 | 2 4d Ga 
, Austria Hungary 2,183.|° °3,163 |. ‘1,765: 4,3050 aie owe 
,, United States of Aanecics L188.) 2.917) 92,69 le O42 855 
,  Other-Foreign Countries 862 349 707 300 212 
Total from Foreign Countries /211,139 |228,410 |233,352 |270,188 286,860 
Total from British Possessions 953 | 2,964) 7,297 753| 1,795 
Total oa ele) 931,374 240,649 [270,941 |288,655 
CHEMICAL, WET. 
Tons. Tons. Tons. Tons, Tons, 
| From Sweden 7,112) 6,948) 7,261 | 13,295 1)916,310 
SiN Ofwa ye. ; “17,6(3.) AVAIL 4) 9,109 | a eae 
Pemother Foreign Countries 10 As 10 
Total from Foreign Countries 24,785 18,075 16,370 99.164 | 27,296 
Total from British Possessions : . ae 
(Canada) 19 950 
Total 24,785 | 18,094 | 16,370 | 22,314 | 27,296 
MECHANICAL, DRy. 
: Tons, Tons. Tons. Tons, Tons. 
From Russia 33199) 42,776 | 1,999)" 08 7a ae 
» sweden . 2,984 3,922) 1,986) 2.4287) 3-510 
a Norway 2,811} 3,553 | - 2,733 2,593 2,192 
,, Other Foreign Countries 154 16 | 11 10 
Total from Foreign Countries| 9,148 | 10,267) 6,669) 6.069| 8,073 
Total from British Possessions 
(Canada) Bl 1,453 
Total 9,199 | 10,267 6,669.) 6,069) 97626 


IMPORTS OF WOOD PULP INTO GREAT BRITAIN 177 


9? 


9 


QUANTITIES. 

1904. | 1905. | 1906. 1907. 1908, 

Mrcu ANICAL, WET. Tons. Tons. Tons. Tons. Tons. 
From Russia 0,452 | 2,614] 1,686] 2,899; 2,608 
» sweden _| 30,741 | 32,940 | 31,212 | 43,610 | 46,019 
ENG ae | /224,620 (202,249 229,202 |262,256 277,988 
5, Germany : : : 25 20 a 645 799 

Other Foreign Countries (ie: 182 64 220 

Total from Foreign Countries |260,912 |238,010 |262,164 [509,630 |327,414 
From Canada . : f 62,957 | 80,236 | 80,959 | 63,545 | 95,548 | 
Other British Possessions 31 Se 2 oh 
Totel from British Possessions | 62,957 | 80,267 | 80,959 | 63,545 | 95,543 | 
Total . (823,869 |818,277 348,123 |373,175 422,957 


(ee a Se ee ee 


CHAPTER VI 
NEWS AND PRINTINGS. 


THE applications of wood pulp, though large and of first- 
rate industrial importance, are not numerous. Its utilisa- 
tion, however, in paper-making is essentially one of great 
influence, and in point of fact this industry at the present 
time dominates the wood pulp market. In this country 
there have been several well-marked phases of expansion 
of the industry. A prominent landmark was _ the 
repeal of the duties on paper in 1860. By a coincidence 
this indirect condition of expansion synchronises with 
the introduction of esparto grass to develop rapidly into 
an important staple raw material, almost a generation 
in advance of the wood pulp age. By the year 1880 the 
importation of esparto had reached 200,000 tons, and it is 
a somewhat remarkable feature of this industry that the 
consumption of esparto has shown no growth from this 
fioure. 

The wood pulps have been independently developed. 
“Mechanical” wood pulp or ground wood dates back to the 
period 1850—60. The chemical pulps in this country were 
pioneered by C. B. Ekman in collaboration with George Fry 
in the period 1870—80. ‘This early venture was capitalised 
by Thomson, Bonar & Co., and worked at Bergvik, Sweden, 
and Ilford, Hssex. The new industry attracted other pioneer 


NEWS AND PRINTINGS 179 


workers, notably E. Partington in this country, and C. Kellner 
in Austria, who individually and jointly did much to 
establish the new order during the following decade. It 
requires a little calculation to estimate the growth of the 
industry during this period, 1880—90, since the statistics 
of importation, in the Board of Trade returns, are a complex 
return including ‘“‘ Esparto and other Materials”: it was 
not until 1888 that the returns of wood pulp importation 
were separately recorded. The growth of the wood pulp 
trade from 1880 to 1888 represents an estimated quantity 
of 100,000 tons, and at this later date the industry had 
become widespread and firmly established in Scandinavia, 
Germany and America. The English importation has 
continued to grow, and the figures for the first nine years 
of the century may be cited :— 


’ 


The total world’s production of “chemical pulp.” is fast 
approaching 3,000,000 tons. In taking this statistical view of 
the paper industry we may note the figures arrived at by 
Krawany, for paper consumption per head per annum, in 


Kuropean countries :— 


Keg. Ke. Kg. 
England . 25°3 Belgium . 111 Russia er? 
Sweden . 240 Holland .10°8 Greece ease: 
Finland . 22°56 Italy . ie ior hare i? 128 
Germany .19°7 Denmark . 64 MRoumania. 1°4 
Norway . 163 Luxemburg 4°8 Bulgaria . 1:3 
Switzerland 15:0 Spain. . 44 Bosnia Ae USL 
France .140 Hungary . 3°6  Servia U0 


Austria . Ili: Portupale.. 3°4. 


Another result of this statistical inquiry is the ascertained 
annual increase of the world’s production, which at 53 per' 
N 2 


180 WOOD PULP-AND ITS USES 


cent. is nearly double the estimated increase of other large 
manufactures, viz., 23—84 per cent. These figures are 
taken from an interesting paper by Dr. A. Klein on 
‘Cellulose, Wood Paper, Artificial Silk,” recently published 
(Chem. Zeit., 60, 521-—580 (1910) ). | 

The most significant development in the paper-making 

art and industry founded on wood pulp is in the production 

of ‘‘news,’ and we may take ‘‘ News and Printings” as 
the subject of this chapter, and typical, in fact, of the 
industrial age we live in. 

The enormous quantities of mechanical and chemical 
pulp manufactured to-day are used chiefly in the production 
of “news” and cheap printing papers. 

A modern newspaper contains about 70 per cent. of 
mechanical pulp mixed with 80 per cent. of chemical pulp. 
In addition to the fibrous constituents the paper will also 
contain about 8 to 10 per cent. of china clay, and a small 
proportion of rosin size. As far as the paper mill is 
concerned, the process of manufacture is almost entirely 
an engineering problem, since all the materials used are 
purchased largely in a completely manufactured state, the 
object being to eliminate chemical processes whenever 
possible. 

This is only true of paper mills dependent on outside 
sources for the supplies of pulp and chemicals, but the 
tendency of modern practice in such mills is to reduce 
the question to one of mixing certain ingredients and 
getting the maximum output of paper at a minimum 
cost. 

At the same time chemistry plays an important part in 
the efficient and economical working of a ‘‘news” mill. 


NEWS AND PRINTINGS 181 


From start to tinish every process is controlled by analysis, 
while improvements in the quality of the paper are gradually 
introduced, either by the use of superior wood pulps, or by 
suggestions that arise from a careful study of the systematic 
records kept. 

A general survey of the operations necessary for the 
production of this class of paper will show the intimate 
relation between chemistry and engineering in almost any 
industrial process. 

Power.—The amount of coal consumed averages 18— 
20 cwt. per ton of finished paper. Most of this fuel is 
required for motive power, though a certain proportion 
is used in drying the paper during manufacture. The 
steam engine is employed for this in nearly every paper 
mill, but in a few cases gas engines worked from gas 
producers have been tried. 

The maintenance of an extensive boiler plant on up-to- 
date principles demands the control of the coal supplies in 
the matter of weight received, the analysis of same for 
moisture, ash left on combustion, and calorific value; the 
systematic analysis of the waste gases from the boiler flues 
to prevent careless firing of the boilers, and to ensure com- 
plete combustion; the use of suitable water for boiler 
purposes, involving the utilisation of all condensed steam 
and hot water, and the adoption of some efficient process 
for softening any hard water which must be employed in 
addition. 

All these operations are controlled by simple methods of 
chemical analysis. The theoretical value of a given coal 
supply having been found by analysis, and expressed in 
terms of the heat units available, it should be possible to 


182 WOOD PULP AND ITS USES 


determine what proportion has been expended in useful 
work, the particular stage in the manufacture of the paper 
at which each proportion has been utilised, and finally what 
amount has been wasted. Questions of this kind are of 
great importance, and involve measurements of many factors. 

Chemicals.—F rom what has been said as to the nature 
of the operations involved in the manufacture of the modern 
newspaper, it is evident that the number of chemicals 
properly so called is not very large. Amongst them will 
be found rosin and alkali used for sizing, or some form of 
prepared size; china clay used as a loading; lime for 
the water-softening process; alum and sundry colour- 
ing matters and pigments; acid and bleaching powder ; 
starch, ete. | 

Oils and greases required for lubricating purposes, and 
other supplies connected with economical power, also need 
attention at the hands of the analyst. 

Wood Pulp.—The exact control of the supphes of pulp 
is an important part of the duty of the mill chemist. The 
determination of the air-dry weight of every consignment 
of pulp is sometimes regarded as a mechanical and simple 
task, but it is one of considerable responsibility. All pulps, 
whether delivered in a dry state or in the moist condition, 
require to be tested for moisture. 

Chemical pulps are tested regularly for quality, satires 
larly as to their behaviour with bleach. Some pulps are 
very difficult to bleach, and consume a large amount of 
bleaching powder. In many cases where a white pulp is 
required a ready bleached pulp is used, but this plan is not 
economical since it is cheaper to treat the pulp at the 
paper mill than to buy the material already bleached. 


NEWS AND PRINTINGS 183 


Mechanical pulps vary in quality and freedom from coarse 
fibre. The differences in bulking qualities are very marked 
and may be measured in the laboratory on small samples 
readily. 

Paper.—The examination of the finished paper from the 
machines in regard to its physical properties of strength, 
bulk, finish and sizing is a matter of routine in a well- 
ordered mill. The testing of contract samples in respect 
of actual composition to determine the percentage of load- 
ing, the proportions of mechanical and chemical pulps 
present and the existence of other fibres, as well as the 
usual physical tests mentioned, is a necessity when making 
papers to sample. 

There are many items in manufacture which call for the 
exercise of careful and painstaking research on the part of 
the chemist, and when these technical questions are studied 
exhaustively by him under the needful encouragement of 
the authorities, the information gradually accumulated is of 
the greatest value. The systematic correlation of modifi- 
cations in manufacture, with the improvements in the 
finished paper by proper classified records which can always 
be referred to, is perhaps one of the most important points, 
but one which is almost neglected in the average mill. 


IMPROVEMENTS IN THE MANUFACTURE oF CHEAP NEWSPAPER. 


During the last twenty-five years great progress has been 
made in the production of common paper from wood pulps. 
The contrast between the old and new methods is best 
illustrated by reference to the output of a machine. 

When wood pulp was first used there were few machines 


184 WOOD PULP AND ITS USES 


capable of making a sheet of paper more than 120 inches 
wide at a speed of 200 to 250 feet per minute, with an 
average production of 50 tons per week. ‘To-day the 
modern machine will produce a sheet of paper 170 inches 
wide at a speed of 500 feet per minute, with an output of 
nearly 45 tons per day. 

Preparation of the Beaten Pulp.—The proper proportions 
of mechanical and chemical pulp are first disintegrated by 
treatment in large potchers or special machinery, being 
mixed with a suitable quantity of water, or generally with 
waste waters from the paper machine. The mixtureis then 
transferred to a beating engine capable of holding sufficient 
wet material to produce one ton or more of dry paper, and 
beaten for about thirty or forty minutes. This is a process 
far removed from that which obtains in the treatment of 
rag, when the beating engine giving the best results is only 
capable of holding wet stuff equivalent to 1 to 2 ewt. of dry 
pulp, and the operation is only completed after eight or 
nine hours. 

To the mixture in the engine about 10 per cent. of china 
clay calculated on the dry weight of pulp is added. Rosin 
size to the extent of 1 or 2 per cent. is then thoroughly 
incorporated, and alum added to precipitate the size which 
adheres to the fibres. The pulp is suitably dyed to the 
desired colour by means of pigments or soluble aniline 
colours. 

The subject of the beating of pulp is one of great technical 
importance, since the quality and characteristics of a paper 
are easily altered by modifications in the process of beating. 
In an elementary treatise of this kind it is impossible to 
enter fully into the question, and only a brief indication 


NEWS AND PRINTINGS 186 


can be given of the variations which are obtained as a matter 
of daily routine. 

The main object of the beating process is the proper 
isolation and reduction of the individual fibres after the raw 
material has been sufficiently boiled and bleached. There 


Fig. 22.—The “ Holiander” Beating Engine. 


are many types of machines available for the purpose, but 
all constructed on the same principle, namely, the circu- 
lation of the mass of pulp and water in a narrow trough 
provided with a revolving beater roll which, as it rotates, 
acts upon the mass drawn between the knives of the roll 
and a set of knives fixed on the bottom of the trough. 

The general construction of an ordinary “ Hollander ”’ 


186 WOOD PULP AND ITS USES 


beater is shown in the diagram. ‘The engine consists of an 
oval-shaped vessel divided into two channels by a “ mid- 
feather’ or partition fixed along the centre of the vessel, 
but not extending completely to the ends. In this way the 
oval vessel is divided into two channels. An adjustable 
beater roll, which is a solid cylindrical drum fitted with 
knives projecting from its surface, rotates in one of the 
channels and revolves above a set of knives projecting from 
the bottom of the trough. The engine is filled with the re- 
quired amount of pulp and water, and by the rapid rotation 
of the beater roll the mixture is constantly circulated round 
the troughs of the engine and passes continuously between 
the knives on the beater roll and those which are stationary. 
The fibres are thus completely separated and gradually 
reduced. 

The varied effects produced in beating wood pulps may 
be illustrated by one or two examples. ‘Thus, if soda pulp 
is beaten quickly with sharp knives, the beater roll being 
close down on to the stationary knives, then a soft spongy 
paper resembling blottings is produced. If on the other 
hand, a strong sulphite pulp is beaten slowly for a long 
time—eight or nine hours—the knives being blunt, and the 
beater roll being lowered gradually during the process, then 
a close dense sheet of paper, strong and resembling 
parchment, is obtained. In the latter case the curious 
assimilation of water by the fibre takes place, with a 
production of an imitation parchment paper. 

Probably the beating operation is the most important in 
the various stages of the manufacture of paper, on account 
of the great variations which are possible by altering the 
conditions under which the pulp is beaten, 


NEWS AND PRINTINGS 187 


It is customary in mills where the ordinary type of 
‘‘ Hollander’? is used to pass the beaten stuff through a 
refiner, whereby the fibres, which are more or less inter- 
locked by the beating, are brushed out. The types of 
refiners mostly used in this country are the ‘ Marshall” 
and the “ Jordan.” 

The Fourdrinier Paper Machine.—The pulp after beating 
is ready for conversion into paper. It is discharged from 
the beating or refining engines into large reservoirs or stuff 
chests, of which there are two to each paper machine. The 
contents of one chest are supplied to the machine while 
the second is being filled from the beaters, so that the pulp 
is uniform and ensures the manufacture of a regular sheet 
of even weight and thickness. 

The pulp flows through a number of strainers which 
serve to retain any coarse pieces of pulp and other impurities. 
For the fast-running news machine the strainer is a hollow 
eircular drum, the shell of which consists of a series of 
curved brass plates bolted together, each scored with fine 
slits. ‘The drums revolve slowly and are kept in a state of 
violent agitation, so that the fine pulp passes through the 
slits and the coarse material is retained. The mixture of 
pulp and water flows in a continuous stream on to the 
surface of an endless ‘“ wire.”’ This consists of a wide band 
of wire gauze stretched horizontally over two rolls, known 
technically as the “breast roll” and “couch roll.” The 
stream of pulp is carried forward at a rapid pace, the water 
finding its way through the meshes of the wire, and the 
fibres settle down on the surface of the wire cloth interlacing 
or ‘felting’? with one another. Further quantities of 
water are removed from the pulp by vacuum strainers or 


188 WOOD PULP AND ITS USES 


boxes fixed under the wire near the couch roll, and the 
“web” of paper then passes between the couch rolls which 
compress the fibres, remove a certain proportion of water, 
and give firmness to the sheet of wet paper. 

The most recent innovations which have been introduced 
to facilitate an increased output of paper and at the same 
time an improvement in the strength of the sheet, have for 
their object devices for increasing the speed of the paper 
machine. Amongst these may be mentioned the ‘ Hibel”’ 
method of manipulating the machine wire. Under this 
system the wire cloth upon which the pulp flows is inclined 
at a considerable angle from the breast roll to the couch 
roll so that the material flows downhill, so to speak. By 
this simple device it is possible to obtain a rapid flow of a 
very dilute mixture of pulp containing large quantities of 
water, which latter is easily removed owing to the slope of the 
wire cloth. Another improvement is the substitution of a 
vacuum couch roll in place of the ordinary solid roll hitherto 
employed, thus obviating the use of a top couch roll. The 
wet sheet of paper passes over a large roll, part of the 
surface of which as 14 revolves is submitted to the action 
of a powerful vacuum, so that the excess of water is 
removed from the wet sheet of paper. The fibres are felted 
together and the life of the wire cloth is prolonged. The 
web leaving the couch rolls is drawn through two or more 
sets of press rolls, which serve to compress the fibres into 
a firm adherent sheet. 

The wet sheet of paper then passes over a number of 
drying cylinders, which are heated internally with steam. 
In the earlier machines eighteen to twenty such cylinders 
amply provided all the drying surface necessary, but in the 


NEWS AND PRINTINGS 189 


modern paper machine thirty-two to thirty-six cylinders are 
required to dry the paper completely, owing to the largely 
increased output. 

The drying of the paper is an important item, because it 
is desirable to dry the paper as slowly as possible at a com- 
paratively low temperature. When the number of cylinders 
is limited, a much higher temperature is necessary to ensure 
complete drying of the paper, but in such case, while the 
output of finished paper can be maintained, the strength of 
the sheet is seriously diminished. 

The paper is afterwards passed through calenders in order 
that a surface or finish may be imparted to it. The 
ordinary calenders fixed at the end of a machine used for 
the manufacture of news consist of a number of highly 
polished chilled rolls, and the paper in passing over and 
under, these rolls is further compressed and at the same 
time glazed. 

No further process is necessary for ordinary news, but the 
reels of paper produced at the end of the machine are re- 
reeled and cut into the required lengths and sizes. 


CHAPTER VII 
WOOD PULP BOARDS 


LarGe quantities of mechanical wood pulp are used for 
the manufacture of pulp boards which have many industrial 
uses such as for boxes, packing cases, cards, calendars, 
advertisement goods, pienic dishes and a variety of similar 
articles. 

In some cases the pulp is mixed with stronger fibrous 
material such as jute, hemp, and chemical wood pulp, 
particularly for boxes of high quality which are required 
to withstand rough usage. The heavy stout boards 
frequently used for railway carriage panels are made from 
the best materials and by hand or manual process, the 
sheets being produced on moulds similar to those employed 
in the manufacture of hand-made papers. 

The cheapest qualities of thin boards, of which an 
ordinary tram-car ticket is a typical example, are produced 
on the continuous-board machine, which in general 
construction resembles the ordinary Fourdrinier or paper 
machine. 

For certain grades of pulp boards which cannot be made 
on the continuous-board machine, on account of the 
thickness, a simpler form known as the single-board 
machine is used. | 

The chief advantage of a wood-pulp board as contrasted 


WOOD PULP BOARDS | 191 


with the common strawboard, which it has superseded to 
a large extent, are to be found in its more attractive 
appearance, its cleanliness, and above all its bulk, being 
thick and of light weight. Moreover it has less tendency 
to erack when folded or bent, and when covered with 
coloured paper, the colour does not fade as frequently 
happens with strawboards which have not been carefully 
made. The traces of alkali often present in common straw- 
board produce a decided fading of some aniline dyes. 

Single-board Machine.—Mechanical wood-pulp boards 
of any desired thickness are produced in sheets of definite 
size on this machine. It differs very lttle from the wet 
press used in the manufacture of wood pulp itself, and only 
a brief note of its construction need be given. 

The pulp mixed with the requisite volume of water is 
passed over strainers which remove coarse chips, and 
pumped continuously into a large wooden vat, containing a 
hollow cylindrical drum revolving at a slow rate. 

The surface of the drum consists of fine wire gauze, 
and as the drum revolves, the pulp adheres to the surface 
in a regular and uniform laver or skin, while the water 
passes freely through the meshes of the wire. The layer 
of pulp comes into contact, as it passes out of the water, 
with a travelling felt, and adhering to this, is carried away 
from the vat and drawn between two heavy rollers, which 
squeeze out the excess moisture. As the thin sheet of pulp 
is wound up on the upper roller, it forms a sheet of 
mechanical pulp which gradually increases in thickness, 
and when the desired thickness has been reached the 
sheet is immediately cut away from the roller and put 
aside. ‘The travelling felt passes round the lower roller 


192 WOOD PULP AND ITS USES 


and back to the vat containing the mixture of pulp and 
water. 

The process is continuous, and the sheets obtained are 
then submitted to pressure, thick felts being interposed 
between the sheets of pulp so that the water drains away 
completely. The material in this condition then contains 
about 50 per cent. of dry pulp and 50 per cent. moisture. 
The sheets are dried, glazed, and cut to any required size, 
the final thickness of the boards being determined by the 
pressure applied during the process of glazing. 

Continuous-board Machine. —This is a combination of 
the single-board machine and the ordinary paper-making 
machine, and is used for making “ duplex’’ and “ triplex ” 
papers. The beaten pulp is formed into thin sheets in 
two or more vats, and these sheets are brought together 
between rollers so as to produce one sheet of the required 
thickness. The board then passes over a large number of 
steam-heated cylinders, and completely dried. The dry 
board is also glazed and finished by calenders fixed at the 
end of the machine, and finally cut up into sheets. 

No further operations are necessary, the finished board 
being manufactured and completed by the one machine, 
the processes following one another automatically. 

Machines of this kind are frequently fitted with more 
than two vats, and in such cases some of the vats are filled 
with common waste material, while two are filled with a 
high-class well-bleached pulp. In this way, a good board 
can be produced cheaply, consisting of a low-grade middle, 
covered on either side with a paper of good quality. 
The colour of the outer surfaces of the board can be 


varied. 


WOOD. PULP BOARDS 193 


Box-MAKING. 


The great demand for boxes as a convenient substitute 
for brown paper in the wrapping and packing up of goods 
has resulted in the creation of an important industry. 

Raw Materials.—The boxes are manufactured from straw- 
boards, wood-pulp boards, and “leather” boards. The 
nature of the composition of the raw material may generally 
be gathered from the descriptions applied, though the term 
“leather boards” is somewhat misleading. Many of the 
so-called boards are made from various kinds of specially 
prepared wood pulp, but in some cases a small proportion 
of leather clippings is incorporated with vegetable fibres by 
suitable treatment. 

The cheap flimsy folding boxes used for wrapping medicine 
bottles and similar temporary purposes are made from 
common board which contains little more than waste 
paper. The boards are brittle and do not stand much 
folding. The leather boards, on the other hand, are 
wonderfully strong and tough, capable of being bent and 
twisted into all kinds of shapes. 

Classification—The different kinds of boxes made in 
large quantities from the raw materials described may be 
classified as follows :— 

(1.) Plain square-shaped boxes, with corners pasted, and 
finished off with plain or ornamental paper. 

(2.) Square-shaped boxes, corners wire stitched. 

(3.) Square-shaped boxes, with metal-edged corners. 

(4.) Folding boxes. 

(5.) Round boxes, made up or stamped. 

(6.) Tubes and small cylindrical cases. 

W.P. a) 


194 WOOD PULP AND ITS USES 


Plain Board Boxes.—The boards are first cut into 
convenient sizes, on an ordinary cutting table worked by 
hand, or in a rotary millboard cutting machine worked by 
power. In the rotary machine a large board can be cut 
up into a number of strips of the required length by means 
of circular knives fitted on to the shaft of the machine, 
which knives can be adjusted to any desired degree of 
accuracy. The strips obtained from the cutter are 
afterwards reduced to the required width. 

The square pieces of board are next scored, that is to 
say, slight cuts are made on the board where the sides are 
bent up to form a box. If the pieces of board are not 
scored in this way they crack and break when bent into the 
form of a box. Machines are also employed in which the 
cutting and scoring are carried out simultaneously. 

After the boards have been scored the corners are cut 
out by simple stamping machines and the box at once 
made up. The operator bends over two edges of the board 
to form a right angle, and places the corner thus formed in 
a stamping press which presses down a small piece of 
gummed paper of the proper length round the corner 
fastening the two edges together. This operation is repeated 
four times in the making of the boxes. The lid of the box 
is manufactured in a similar manner, due allowance being 
made in the cutting of the board in order to obtain a well- 
fitting lid. 

The boxes are left plain, or finished off with printed 
labels and ornamental paper. 

The covering of boxes with ornamental paper is a simple 
process, the variations being not so much in- the methods 
employed as in the materials used. Most of the boxes used 


WOOD PULP BOARDS 195 


by drapers are generally covered with a flint-glazed box 
paper, the edges of the boxes being finished off with 
coloured paper of a similar character. The edges of the 
boxes are first covered with thin strips of paper either by 
hand or by machinery, the top and sides of the box being 
afterwards covered with the white glazed paper in such 
a manner as to leave the coloured edges of the box 
exposed. 

Boxes produced in this way in large quantities are finished 
by means of a “banding’’ machine in which a reel of 
slazed paper is gummed on one side and drawn on to the 
box which is automatically turned four times by the 
machine and thus covered. 

Wire-stitched Boxes.—The board used for this class of 
box is cut into required sizes and either scored or dented. 
In the latter case the board is passed through a denting 
machine which stamps a slight depression along the line 
which is to form the corner of the box. 

The ends of the board are then slotted so that the box 
can be produced by being turned up into shape along the 
lines formed by the denting machine. The ends are then 
fastened together by. the wire stitching, in which process 
small pieces of wire are forced through the ends of the 
box and clinched. 

Metal-edged Boxes are generally manufactured from 
good material, such as leather. boards, because they are 
intended for constant use. The boards are usually grooved 
along the bending line, either with a square groove or with 
a deep V-shaped groove, the latter being preferred as giving 
the box a neater finish at the corners when completed. 
The edges of the box and the joints are finished off with 

0 2 


196 WOOD PULP AND ITS USES 


metal edging which consists of a thin strip of metal stamped 
out and provided with sharp projecting points. When this 
strip is forced into position the projections pass through 
the board and being turned up by the machine are firmly 
clinched. ‘The boxes made by this process are very strong 
and present an attractive appearance. 

Folding Cases.—The cheap common cases used for 
packing eggs, patent medicines, and similar articles of 
domestic use are stamped out from thin cardboard by 
machinery. The general shape and outline of the boxes 
having been calculated, a metal forme or template is 
prepared, by means of which the outline of the box can be 
stamped out. 

The forme resembles in principle that used by a printer, 
but instead of raised type, strips of brass are used and also 
pieces of hardened steel. When the thin board is placed 
on the forme and submitted to pressure, the brass strips 
indent the board along the lines which are to form the 
edges of the box, and the steel knives cut out the portions 
of the board which are not required. The two edges which 
overlap to form one side of the box are fastened together 
with wire stitching or with glue. In this condition 
the box can be folded flat, and when required for use 
it can be opened up and put together as a box very 
quickly. 

Postal Tubes, ete-—The many varieties of cylindrical 
boxes made for postal work, the packing of gas mantles, 
phonograph records, carbon paper, blue print and photo- 
graphic papers, and similar purposes, are made by covering 
one side of a board with glue or some adhesive material, 
and rolling the board up into the form of a tube on an 


WOOD PULP BOARDS 197 


iron roller, the diameter of which varies according to the 
size of the bore of the tube. | 

For short boxes the long tubes are cut up into stated 
lengths. The caps for these tubes are stamped or pressed 
out of circular discs of flexible leather board. The whole 
operation is exceedingly simple and does not seen: any 
elaborate explanation. 


CHAPTER VIII 
THE UTILISATION OF WOOD WASTE 


Vanrous methods of utilising wood refuse are in practice, 
chiefly based on chemical processes. The only commercial 
application of waste wood based on a simple mechanical 
treatment, and now an extensive industry, is the manufacture 
of wood wool. 

Wood Wool.—This is an elastic material much used for 
stuffing cushions and mattresses; for packing glass, hard- 
ware, and fragile goods; for filtration, and many other 
purposes of diverse character. It is very light and bulky, 
not easily reduced in volume when wetted, and is thus 
eminently suited to these and similar uses. 

Any small odds and ends of wood from carpentering and 
cabinet workshops up to 14 or 16 inches long can be 
utilised. 

Special machinery has been devised for converting pieces 
of wood of all shapes and sizes into shavings of desired 
thickness. The pieces of wood are fed to the machine by 
hand. They are seized by rollers which carry the wood 
forward automatically, bringing them under planing irons 
and also in contact with pointed knives, the thickness of 
the shaving being determined by the setting of the plane 
irons and the width of the shaving being fixed by the 
position of the knives which produce cuts in the wood parallel 


THE UTILISATION OF WOOD WASTE 199 


to the lengh. One machine is capable of producing 6 to 12 
cwt. of wood wool in twelve hours. 

Sawdust.—Large quantities of sawdust are produced in 
many industries, and the profitable utilisation of this waste 
material depends largely upon the quantity periodically 
available. When the amount is small, it is best utilised as 
an ordinary packing material, but for this there can only 
be a limited demand. Some idea of the varied uses of saw- 
dust may be gathered from the following brief description 
of the methods in use. :, 

Sawdust thoroughly mixed with common rosin is con- 
verted into fire-lighters. 

Mixed with highly concentrated artificial manures, it 
serves as a medium for manurial purposes. The sawdust 


itself has no value as a fertiliser, but it has a capacity of 
absorbing and retaining liquids. Occasionally the sawdust 
is first converted into charcoal. 

Sawdust has also been employed as the source of the 
carbon in calcium carbide. The sawdust is first converted 
into charcoal, which is mixed with limestone, and the 
mixture heated for several hours in an electric furnace. 

In limited quantities, sawdust is also converted into 
paper pulp, but the fibre is exceedingly short and of little 
value, and it is difficult to obtain an evenly boiled material 
owing to the difficulty of maintaining a proper circulation of 
the caustic soda, lye, or other reagent in the digestor. 

Sawdust is also mixed with the concentrated waste 
liquors from the sulphite wood-pulp manufactories, and 
then converted into briquettes. These briquettes can be 
used as fuel or submitted to distillation for the manufacture 
of wood spirit, acetic acid, and charcoal. 


200 WOOD PULP AND ITS USES 


Producer Gas from Wood.—An interesting application of 
the use of waste wood is to be found in the generation of 
‘“‘ nower gas.’ In Riche’s gas-producer the wood is heated 
in two suitable retorts, one of which is used for the distilla- 
tion of the wood, and the second for the decomposition of 
the gases obtained by the distillation of the wood in the 
first retort. The combustion is first started in the second 
or reducing retort. When the heat has been raised to the 
proper extent, the distillation is commenced in the first 
retort. The charcoal produced is withdrawn periodically 
from the bottom of the first retort and thrown into the 
reducing retort. The distilled gases from the first retort 
are passed through the heated charcoal placed in the 
second, and subsequently into the gas holder. The gas 
produced has a heating value of about 340 B.T.U. per cubic 
foot, the quantity of gas per 100 kilos. of wood being 100 
cubic metres, or about 16 cubic feet of gas per pound of 
wood. 

Donkin * states that about 100 small plants of this type 
have been erected in France and some of the French colonies. 
An interesting example is to be found in Madagascar, where 
gas obtained in this way is utilised in two gas engines of 
15 and 8 h.p. respectively for the manufacture of artificial 
ice, the cost of the motive power being one-third of that 
obtained by usual methods. . 

Oxalic Acid.—Sawdust and other forms of wood waste 
yield oxalic acid when treated with caustic soda. Forty 
parts of sawdust are mixed with strong caustic soda of 
specific gravity 1°35, and heated in shallow pans until the 
temperature rises to 220—240° C. The product contains 


1 «Gas and Oil Engines.” 3B. Donkin. 


THE UTILISATION OF WOOD WASTE 201 


carbonate of soda and sodium oxalate. This is dissolved 
completely in boiling water, and the strength of the solution 
carefully regulated, so that on cooling, the sodium oxalate 
erystallises out. The mixture is then treated in the hydro 
extractor to remove the liquid. 

The crystals of sodium oxalate are dissolved and treated 
with milk of lime, and thereby converted into calcium 
oxalate. The latter product is precipitated, separated from 
the liquor by filtration or any suitable means, and repeatedly 
washed with water. 

The calcium oxalate is then decomposed by treatment in 
a lead-lined vessel, with strong sulphuric acid, the whole 
mixture being heated with steam, and maintained at the 
boiling point for some time. The oxalate is decomposed, 
giving, after treatment with the sulphuric acid, a precipitate 
of calcium sulphate and a solution of oxalic acid. The 
precipitated calcium sulphate is removed, and the solution 
carefully evaporated for the production of crystallised 
oxalic acid. 

The amount of oxalic acid obtained may be varied 
according to the method of heating. Thus the percentage 
yield is increased by using potassium hydrate as well as 
sodium hydrate, and also by heating the material in thin 
layers. The yield of oxalic acid from various woods is as 


follows :— 
Spruce. 94°7 
Poplar ; 93°0 
Beech.-~ . 86°3 


Oak . ; 84-4 


202 WOOD PULP AND ITS USES 


Tur Destructive DISTILLATION oF Woop. 


When wood is burnt under conditions which restrict the 
supply of air, or heated in closed retorts, it passes through 
a process of destructive distillation with the production of 
certain valuable commercial substances. 

The combustion of wood in a confined space was resorted 
to in early days for the manufacture of charcoal simply, 
and large quantities of this charcoal are produced even 
to-day by the primitive method of stacking wood, covering 
it with earth and setting fire to the wood at the bottom of 
the pile. The only substance obtained was the charcoal 
left when the process was completed, but about 1812 the 
discovery of the presence of wood spirit and acetic acid in 
the vapours given off, led to a closer study of the chemical 
changes taking place. | 

The products of distillation are chiefly acetic acid, wood 
spirit (methyl alcohol) tar, gases and charcoal. By slow 
distillation at a low temperature a maximum yield of acetic 
acid and tar is obtained. The gas given off during the 
operation, a mixture of carbon dioxide and carbon mon- 
oxide, is utilised by passing it through the furnace employed 
in heating the retorts. The carbon dioxide is reduced to 
monoxide, a combustible gas which gives off its available 
heat in the furnace. 

By rapid distillation at a high temperature, the volatile 
products are decomposed giving a greater yield of gas and 
a smaller proportion of acetic acid. 

The effect of the method of heating is shown in the 
following table taken from Fischer’s Chemical Technology. 
In the slow distillation process, the wood was heated slowly 


THE UTILISATION OF WOOD WASTE 203 


for six hours, starting with cord retorts, while in the fast 
distillation the wood was placed at once in heated retorts 
and treated for three hours. 


Percentage yield of distillation products. 


Wood % pure : 
Wood. distillate. Tar. Aa Oy | peas shivenad Pe 
Birch— 
slow . 51°05 5°46 45°59 5°63 29°64 Toe 
fast . 42°98 3°24 39°74 4°43 21°46 30°06 
Beech— 
slow . 51°65 5°85 45°80 ed. 26°69 21°66 
fast 44°35 4:90 39°45 3°86 21:90 30°10 
Oak— | 
slow : 48°15 a210 44°45 4:08 34°68 il 
Taste: 45°24 3°20 42-04 3°44 20°10 27 'Ua 
Larch— 
slow os “ig Wen | 9°30 42°31 2°69 26°74 21°65 
fastes.: <3 43°77 5°58 38°19 2°06 24°06 a2° 17 
| Spruce— 
SLO Ses 46°92 5°93 40°99 2°30 34°30 | 18°78 
fast . 46°35 6°20 40°15 178 24°24 29°41 


In practice the distillation of wood is carried out with 
due regard to the nature and quantity of the desired products, 
and the method of treatment varied accordingly. 

Steam Distillation. — With pine and woods rich in 
turpentine oils the material previously reduced to the 
condition of small chips is heated by means of steam in 
closed vessels at a pressure of 40 lbs., and the oils distilled 
off by the steam. 

This process is usefully employed in the pulp mill, since 
the manufacture of paper pulp from pine wood can be con- 
ducted in such a way as to ensure the extraction of the 
turpentine from the digestors and the subsequent conversion 


204 WOOD PULP AND ITS USES 


of the wood into pulp. The soda process of paper-making 
is easily adapted, for the ordinary steam pressure is sufficient 
to drive off all the volatile oils, and most of the resinous 
matters are converted into soluble soda compounds. 

Dry Destructive Distillation.—The products obtained from 
different woods as determined by the Bureau of Chemistry, 
Washington, are shown in the following table :-— 


Average yield per cord of wood (128 cubic feet piled wood). 


, Resinous Hard wood 
Hard woods. woods. sawdust. 
| Charcoal (bushels). ; 45 30 30 
Crude wood spirit containing 


acetone (gallons) . ; 10 
Acetate of lime (lbs.) : ; 75 120 60 
| Tar (gallons) : : : 15 
Wood oil (gallons) — 
Turpentine (gallons) — 


In the slow distillation process, a maximum yield of solid 
product is aimed at, with a minimum quantity of gas. 
Harper gives the results of a test on dry yellow pine :— 


Yield per cord, air-dry. 


Gallons. lbs. os 

Turpentine. : ; 18°64 134°20 3°679 
Wood oil , , ; 11°09 86°50 oS 14 
Pars A : ‘ : 96°0 846°72 23°216 
Acid : : 2 : 96°0 830°49 DIET 
Cake ; . : ; — 14°74 404 
Charcoal . ; — 796:00 21°826 
Yellow oil and pitch A 6°78 57°02 1°563 
Gas and Loss . : , — 881°33 24°170 

3,647°0 100°000 


THE UTILISATION OF WOOD WASTE 205 


With the rapid distillation method, a maximum yield of 
eas is obtained, and in this case the process is utilised for 
the manufacture of illuminating gas or for power gas. All 
kinds of waste wood material such as sawdust are turned 
to good account in this way. 


CHAPTER IX 
TESTING OF WOOD PULP FOR MOISTURE 


In the selling and buying of wood pulps the question of 
associated moisture is of obvious importance, regulated by 
convention and by standards, it requires to be controlled 
by actual tests. The mechanical wood pulps are generally 
shipped from the mills in the form of bales containing 
moist pulp on the basis of 50 per cent. air-dry pulp. The 
chemical pulps are shipped usually in bales containing the 
air-dry pulp. 

Disputes frequently arise as to the exact air-dry weight of 
pulp received, the chemical pulps frequently containing 
moisture in excess of the standard, and the mechanical 
pulp also containing a larger amount of moisture than 50 
per cent. 

No satisfactory standard method has yet been found for 
the sampling and testing of wood pulp. When the freshly 
made bales are shipped from the pulp mill so that the 
whole of the sheets in the bale are uniform, then it is 
comparatively easy to take samples from the bale which 
shall fairly represent the pulp. If, however, the distribu- 
tion of moisture in the bale has been altered to any extent, 
either by loss in weight owing to the drying of the outer 
sheets and exposed edges of the bale during prolonged 


TESTING OF WOOD PULP FOR MOISTURE 207 


storage, or on the other hand if the bales have become 
much heavier by accidental wetting through rain or other 
causes, then the sampling is by no means an easy matter. 

Frequently the water in the bale freezes, and in conse- 
quence of this much of the water is drawn from the interior 
of the sheets and deposits itself as a layer of snow or ice 
between the sheets which lie upon one another in the 
bale. 

The bale when opened falls apart most readily just at 
those points where the surface of the sheet is covered with 
ice, and it is almost impossible under such circumstances 
to take out samples that shall fairly represent the whole 
bale. Jiven when this ice has thawed out sufficiently to 
resume the form of water, it does not distribute itself 
evenly through the pulp for a very long period. 

General Principles.—A certain proportion of the bales 
which form a consignment are selected for the test. 
Usually 4 per cent. of the number of bales are taken, due 
care being exercised in the selection so that the bales are 
sound, in good condition, and do not exhibit any serious 
deviations in gross weight. 

The selected bales are weighed and sampled. The 
samples as cut are immediately put into bottles, or tins, 
which are sealed up and taken to the laboratory where 
they are dried at a temperature of 160° C. and the percent- 
age of absolutely dry pulp determined. The weight of 
air-dry pulp is calculated from this figure on the arbitrary 
basis that 90 parts of absolute dry pulp give 100 parts of 
air-dry pulp. 

The analyst gives a certificate in accordance with the 
following schedule :— 


208 WOOD PULP AND ITS USES 


Woop Putpe Moisture CERTIFICATE. 
(Form adopted by the British Wood Pulp Association.) 


THis 1s TO Crertiry that I have tested for moisture a 
parcel of 
Pulp, said to consist of bales, marked 
lying at 


The samples were drawn by me on 
; ; Bales. T. Cwt. Qrs. Lbs. 
Total gross weight of bales sampled (intact) 


(For numbers and detailed weights see below.) 


Weight of Parcels calculated from above . 
Percentage of absolutely dry pulp in the 
sample ; 5 : : per cent. 
moisture in the sample . d * 
air-dry or moist pulp in the 
parcel on the basis of 


90=100 (air-dry) . i 
45=100 (moist) . ip 
excess Moisture, Fibre . 


T. Cwt. Gan Lbs. 
Weight of Pulp to be invoiced . 


NUMBERS AND DETAILED WEIGHTS OF BALES SAMPLED. 


Analyst. 


Difficulties in Sampling.—tIn practice it is found that the 
testing of wood pulp for moisture offers many difficulties. 
The uniformity of the moisture throughout the bale is 
seriously disturbed by the causes already described so that 
not only is it difficult to select really representative bales, 
but the work of cutting out samples is also complicated. 

Various methods are employed for taking out samples of 
pulp, and at present there is no standard method, although 
attempts have been made to establish a uniform system. 


TESTING OF WOOD PULP FOR MOISTURE 209 


It is scarcely necessary to enter into any prolonged 
discussion as to the merits of the various methods each of 
which are no doubt correct under certain conditions. With 
pulp that has not been in stock more than three or four 
weeks any reasonable system would give correct results, but 
the difficulty is to find a system which woukl give correct 
results on freshly made pulp and exactly the same results 
on the pulp after having been in stock several months. 

Probably the system which finds general favour is that 
known as the “‘ wedge” method, in which it is assumed 
that a wedge having its apex at the centre of the sheet of 
pulp and a base of any desired width at the outer edge of 
the sheet of pulp represents the sheet itself, taking the 
correct proportions of the inner and outer sections of the 
sheet. ‘This may be explained by reference to the diagram 
in Fig. 23. 

Let ABCD represent a sheet of air-dry pulp of uniform 
thickness, measuring 24 inches by 18 inches, and divided 
into four equal parts—H, the inside portion; H, the outer 
portion ; and F, G, intermediate portions, thus :— 


Square inches. 


Area EK = AP So LOD 
Areas HK, F SLO UO relent ee ——_ ALOU 
Areas E, F, G As OD Xe ee bOoe— 524-0 
Ayoas tune. Pha Dare X13] = 432°0 
Square inches. 

K =:-108 

a Ais: 

G7 108 

rie 108 


Total== "432 


WOOD PULP AND ITS USES 


Rn ee nee ne Ol en eens 


" 


Ag-s2----— =  H - = 24 


23. 


Fic. 


ile Sele ees 


Fig. 23. 


TESTING OF WOOD PULP FOR MOISTURE 211 


The dimensions of the various rectangles are all propor- 
tional, that is, the ratio of the length to the breadth is the 
same in all cases, viz., 24 to 18. 

A sample from the sheet which shall represent the whole 
is obtained by taking equal areas from each of the pieces 
EK, F, G, H; but in practical testing such a course is 
impossible, as it would necessitate marking the exact 
position of the “lines of separation” before the small 
pieces of equal area could be cut. Another alternative 
would be to cut a quarter sheet from the whole—an equally 
impracticable scheme. But a wedge gives four equal-sized 
pieces from the four areas H, I’, G, H. 


Let such a wedge having a base of, say, 2 inches, be 
drawn as shown in Fig. 23. Let Fig. 23a represent the 
wedge on an enlarged scale, consisting of the four areas e, f, 
g, h. The area of the whole sheet is 24 inches by 18 inches, 
or 432 square inches, and the areas of the wedge is that of a 
triangle whose height is 9 inches and whose base is 2 inches. 

The wedge contains a series of triangles, viz., (1) the 
triangle e; (2) triangle consisting of pieces e f; (8) triangle 
consisting of e, f, g; (4) triangle consisting of pieces e fg h. 
By calculating the area of each triangle the exact size of the 
separate pieces e, f, g, h is found. 

The height and base of each triangle is easily cal- 
culated :— 


(1) Base of triangle e Height of triangle ef 
Base of triangle (efgh) Height of triangle (efgh) 
Base of e 46 


= — giving 1:0 inches. 
2 9 


212 WOOD PULP AND ITS USES 


(2) Base of triangle ef Height of triangle ef 


Base of triangle (efgh) Height of triangle (e¢fgh) 
Base of ef  —- 6865 
— = - giving 1°4144 inches. 
2 $; 
The other triangles are treated in a similar manner and 
the areas readily calculated. 
(Area of a triangle = 4 base x height.) 


Square Inches. 


Triangle hgfe has area 4 (2 X 9) io 
yh KZ eb eea(1s7815 <7 1925 ea 
HL ye e(1:4144 X-6°365) — eo 
ee: Fee uh ees) — 9°25 


From the above figures the areas of the pieces e, f, g, h, 
are :— 
Square Inches. 


€—— 220 
fp Spay. 
Og ——e2l20 
i RS 


Hence any sized wedge contains what the pulp maker 
defines as correct proportions of ‘‘ inside and outside pulp,” 
at any rate mathematically. 

Absolute Dry and Aw-dry Pulp.—The exact air-dry weight 
of pulp is calculated on the basis that 100 parts of air-dry 
pulp consists of 90 parts absolute dry pulp and 10 parts 
of natural moisture. This is an arbitrary figure based 
on the assumption that air-dry pulp contains 10 per cent. 
of natural moisture. As a matter of fact the air-dry 
weight of pulp varies according to the conditions of the 


TESTING OF WOOD PULP FOR MOISTURE 213 


atmosphere, but for trade purposes the arbitrary figure 
selected is convenient. 

In 1896 Sindall made some experiments with a view 
of determining the influence of the atmospheric moisture 
upon the weight of wood pulp. Numerous samples were 
exposed to ordinary atmospheric conditions for nearly two 
years, the samples of pulp being weighed two or three times 
a week and the relative humidity of the air being also noted. 
The following table was compiled as the result of these 
experiments, showing the air-dry weight of the exposed 
pulps, the actual absolute dry weight of pulp being 88 parts 
in each case. | 


SHOWING THE, VARIATION OF THE WEIGHT OF PULP DUE TO 
MOISTURE IN THE AIR, 


ee pan Mechanical Pulp. page Soda Sulphite Pulp. 

Average. Average. Average. 
o1°4 99°03 95°98 96°53 
60°00 100°04 96°42 96°85 
65°30 100°42 96°91 97°45 
taeeU 102°24 98°60 99°30 
80°15 102°41 98°21 99°50 
82°10 102°78 98°41 99°74 
82°70 102°58 98°70 99°69 
82°90 102°84 98°78 99°80 
83°20 103°56 98°95 100°50 
83°90 103°17 98°98 100°68 
85°10 103°81 99°42 100°60 
86°60 105°138 100°41 101°638 
87°50 104°55 99°92 101°04 
§8°24 104°64 100°23 100°93 
89°10 104°63 100°02 101-14 
90°00 105°40 100°70 101-90 
93°00 106°82 102°40 103°76 


The exact relation between the humidity of the air 
and the air-dry weight of wood pulp as determined 


214 WOOD. PULP AND ITS USES 


by these experiments may be expressed in the following 
Ooms | | 

If the numbers representing humidity form a series in 
arithmetical progression, then the weight of wood pulp 
corresponding to those numbers produces a series of figures 
in geometrical progression, thus :— 

Humidity = H, H + d, H + 2d, H 4+ 3d, H + 44d, 
Weight = W, Wr, Wr’, Wr’, Wr, 

Where digress, 

If the results given in the table are plotted in the form 
of a curve, it is possible to correct the errors of observation 
and determine the air-dry weight of pulp for every 5 degrees 
difference in the humidity of the air. 


SHOWING THE VARIATION OF THE WEIGHT OF PULP FOR EACH 
5 DEGREES INCREASE IN THE HUMIDITY OF THE AIR. 


Air-dry Weight of Pulp. 
Relative Average 
Humidity. ; difference Constant r. 
H. Mechanical. a ae and Sulphite. for bi. 
a0) 98°95 95°90 96°35 0°26 —- 
00 99°30 96°10 96°60 0°33 1°25 
60 99°70 96°39 96°95 0°42 1227 
65 100°20 96°65 | 97°40 0-52 1°24 
70 100°80 97°05 97°95 0°68 1°30 
75 101°60 97°60 98°68 0°82 1°30 
SO 102°50 98°30 - 99°50 Peas | 1°35 
8d 103°75 99°38 100°60 1°52 1°34 
90 105°25 100°80 102-20 — ae 
Mean=1:28 
| 


CHAPTER X 
WOOD PULP AND THE TEXTILE INDUSTRIES 


Tue celluloses and compound celluloses are produced in 
definite and characteristic structural forms, and only in such 
form. By chemical processes such as described in Chapter IL., 
we may convert the original structural celluloses into its 
amorphous or structureless forms by way of solutions of 
derivative compounds. It is clear, however, that questions 
of form and dimensions underlie every technical problem 
involved in the applications of cellulose. 

The following are the dimensions of the more important 
celluloses, considered as ultimate fibres. 


Length of Fibre. Diameter. 

Cotton 20—40 mm. — 
ine x Flax 25—30 ,, 0:015—0-037 
‘ine textiles. Rhea 60—200 ,, 0:030—0-070 
rian 15—25 ,, 0:016—0-050 
Jute 15—4:0 ,,_ 0°020—0-028 
Coarse textiles Sisal 1:5—6°0 ,, 0°015—0:026 
and Rope-making. }) Phormium o'0—18°0 ,, 0°010—0-°020 
Breecad (Tracheids) 1:°0—20°0 ,, 0°015—0-020 
Paper-making Esparto 05—3:0  ,, 0°010—0-018 


It is somewhat remarkable that the most important 
cellulose, cotton, occurs and is industrially worked as an 
ultimate fibre or structural unit. 

Incidentally, it is worthy of mention that cotton is a seed 
hair, and in physiological function therefore, being con- 
cerned with a usually perishable tissue, it is not a priori 


216 WOOD PULP AND ITS USES 


associated with permanence. On the same grounds and 
for the contrary reason we should expect to find in the 
wood substances which have long continuing or perennial 
functions, a chemical constitution implying superior 
stability. The paradox, however, holds that cotton is our 
type of chemically balanced cellulose and of a higher order 
of stability than the wood celluloses. 

To complete this point we must refer the reader to the 
previous section, which deals with the conditions of per- 
manence of the ligno-celluloses which are natural compound 
forms. We have to remember also that a wood cellulose is 
a residue always of chemical processes. 

As regards structure the woods are highly complex, 
whereas most of the textile fibres mentioned above are 
either bast fibres (bundles) or fibre vascular bundles. In 
the former case, as in flax, rhea, and hemp, the bundle is 
simple. It is more complex in the case of jute (see 
Chap. I.), and still more complex in the fibre vascular 
bundles of monocotyledons. 

Ksparto is a heterogeneous aggregate as in the case of 
the woods. 

In the mcre complex structures the celluloses are 
associated with various chemical groups (compound cellu- 
loses), which are attacked and removed by the various treat- 
ments of hydrolysis and oxidation by which the celluloses 
are isolated. For our present purpose we are concerned 
only with the celluloses in the form of ultimate fibres. 
These are the unit elements of structure of the yarns and 
threads which are the basis of textile fabrics. The 
mechanical properties of these, as well as the processes by 
which they are mechanically prepared and ultimately spun, 


WOOD PULP AND THE TEXTILE INDUSTRIES 217 


are obviously determined by their simpler elements of form— 
that is, their dimensions. 

The mechanical principles involved in the production of 
fine textile yarns from these discontinuous units, are first, 
the reduction of these to a common untwisted. sliver, in 
which they are parallelised; secondly, the drawing and 
twisting of the fibres composing the sliver in continuous 
length. 

The tensile properties of the resulting yarn depend mainly 
upon the twist, partly upon the adhesion of the more or less 
closely-spun fibres. 

There are numerous variations of the process, such as the 
wet spinning applied to bast fibres and notably flax, the 
passage of the sliver through a bath of warm water facili- 
tating the ultimate subdivision of the bundles of fibres 
in the final drawing and twisting operation. In the 
coarser textiles, such as jute, it is evident that the spinning 
unit is an ageregate or bundle of the ultimate fibres, which 
are too short (2 to 8 mm.) to admit of manipulation. 

They are worked in lengths, which have reference to the 
conditions of the machinery, most convenient for preparing, 
drawing, and twisting. But it must be borne in mind as a 
fundamental technical fact that the ultimate properties of 
the yarn are conditioned primarily by the length of the 
ultimate fibre. This will be evident from the table 
(p. 282), giving the relative strengths of textile yarns in 
terms of actual tenacity and apparent elasticity (extensi- 
bility). We have added to the list the new products 
known as artificial silk, or lustracellulose. This being pre- 
pared from structureless solutions of cellulose derivatives 
may be considered as structureless. In this sense they 


218 WOOD PULP AND ITs USES 


resemble the true silks which are produced in solution in 
the glands of the silkworm and extruded into the atmo- 
sphere, the worm performing the mechanical operation 
of drawing and laying the threads in the specialised form 
of cocoon. 

The structureless cellulose, in the form of a thread of 
regular dimension, presents to us a case of mechanical pro- 
perties of a substance independently of the grosser structural 
details which characterise the natural cellulose fibres, and 
it will be seen that cellulose admits of very severe treat- 
ment in passing through a cycle of operations and reverting 
to an amorphous substance which retains much of the 
structural properties of the original. 

Reverting now to the fibrous celluloses, there are certain 
features common to the paper-making and the textile 
industries. Thus, a web of paper and a textile yarn 
may be made from the same raw material, and, more- 
over, have the common characteristic of an agglomerate 
of discontinuous fibrous elements produced in continuous 
length. The strength or cohesion of the two fabrics depends 
in the first place upon the surface adhesion of the fibrous 
units, but in the case of the textile yarn this is a much less 
important factor than the “ twist’? communicated by the 
spinning process. On the other hand the paper web, though 
devoid of twist, presents certain characteristics in the 
opposition and adhesion of its structural units, which makes 
it a more coherent agglomerate than the yarn. Generally 
this is referable to the wet processes of the paper-maker, 
which brings the colloidal fibre substance into a condition 
of hydration or gelatinisation, in which a more intimate 
adhesive contact of the fibre surfaces is determined. ‘he © 


WOOD PULP AND THE TEXTILE INDUSTRIES) 219 


cohesion is augmented by the pressure to which the web is 
subjected while still in the wet state and the union of the 
fibre surfaces is finally cemented by the drying or dehydra- 
tion of the web. Conversely, when re-wetted a paper is 
brought -back into approximately the condition of the web 
as first put together and its cohesion in this state or 
wet-strength, is only a fraction of that of the paper. | 
The cohesion of a textile yarn, on the other hand, is 
only slightly affected by wetting, and the effect indeed 
is not necessarily in the direction of diminishing tensile 
strength. . | 

The main point of contrast between these great divisions 
of manufactures devoted to the industrial utilisation of the 
vegetable fibres, is the length of the unit fibre, or fraction 
of fibre, in the final state of preparation of the raw fibrous 
material. Generally, we may say that the limit of economic 
handling in the textile industry is reached with a length of 
fibre of 83—5 mm. This inferior limit expresses, on the 
other hand, the outside limit imposed upon the paper- 
maker for the satisfactory working of his wet web upon 
the wire cloth of the machine or hand mould, and for the 
majority of papers a length of 1—2 mm. is a working 
optimum. 

This corresponds with an obvious complementary rela- 
tionship of the two industries, and the paper-maker, up to 
fifty years ago, was practically limited, as to raw material, 
to the wastes of the textile industries. 

In later times there have been notable advances in the 
method of working up short fibre wastes by the spinner’s 
dry methods, “‘ ginning process,” and, by special modifica- 
tions of teasing or carding machines, the utilisation of 


220 WOOD PULP AND ITS USES 


these short fibres has been carried to extreme limits. As 
a question of cost of production it is found, however, that 
the paper-making process has considerable advantage. The 
problem then arises of converting the continuous length of 
paper into a textile yarn, with the associated question of 
the actual utility of the product. The elements of the 
problem are these :— 

(1) The subdivision of the web of paper into strips of 
suitable dimensions. | 

(2) The rolling of these strips continuously into the 
cylindrical form. | 

(3) Subjecting the cylindrical length of paper “ felt” to 
a twisting operation so as to increase its tensile strength 
to a Maximum. 

Having by these processes appreciated to a maximum 
the tensile qualities of the fibrous agglomerate, we still 
have to reckon with the intrinsic limitations of quality, 
due to shortness of fibre, on the one hand, and the fact 
that when wetted the product loses its cohesion. 

This is a general and somewhat “ theoretical’’ exposé of 
the technical basis of an industrial movement which has 
been in progress since 1891, toward the utilisation of paper 
in the form of a textile. It may be noted that this move- 
ment, though quite new to Europe, is based upon old- 
world practice, for the Japanese have for centuries used 
paper as a basis of string or twine, twisting paper strips of 
convenient width into the cylindrical form, and also piecing 
successive lengths to produce a virtually continuous fabric. 
This, however, was a manual operation performed upon the 
finished paper, and the product is only crudely suggestive 
of the pulp yarns which have been evolved through various 


WOOD PULP AND THE TEXTILE INDUSTRIES 221 


stages of perfection by the work of EKuropean inventors 
bringing to bear upon the problem the resources of modern 
mechanical appliances. 

The development of this industry is mainly due to the 
enterprise of a succession of German inventors, and an 
excellent account of their labours is contained in the 
treatise of Prof. E. Pfuhl, ‘‘Papierstoffgarne (Zellstoffgarne, 
Xylolin, Silvalin, Miella) ihre Herstellung, Higenschaften 
und Verwendbarkeit,’ published by G. Hoffler, Riga, 
1904. This treatise on ‘ Paper-pulp-yarns, their pre- 
paration, properties and applications,” is a very complete 
technological account of the matter, to which the specialist 
student must refer. In the general account which follows 
we have made free use of the matter of the treatise, and 
we acknowledge our indebtedness to the author and 
publisher. 

It appears that the evolution of the industry is set forth 
in the subjoined outline of inventions, as embodied in 
German patents. Practical success is claimed to have been 
achieved by three of these systems, each of which represents 
a consolidation of two or more patented inventions :— 

(a) The system of Claviez & Co. is based upon a finished 
but unsized paper as raw material. This is cut into 
fine strips, of a few mm.’s width, each strip being separately 
wound on a bobbin, which is then transferred to a spinning 
or twisting frame. In the form of twist it is subject to a 
rolling process to consolidate the thread, and this treat- 
ment is repeated, after moistening the thread, in a second 
machine, the speed of which is adjusted to produce a certain 
drawing effect. 

The spindle designed by Claviez for the spinning or 


222 WOOD PULP AND ITS USES 


twisting of the paper strips is represented by the accom- 

panying figure (Fig. 24), the spool or reel carrying the 

paper strip of 2—3 mm. width is carried on the hollow 

brass axis b, which is held in position on the spindle s by 

means of springs. The fliers f rotate in the same direction 
in which the paper strip was wound 
on the spool; the strip is thus twisted 
and drawn off through rollers under 
suitable tension. The yarns pro- 
duced under this system are known 
as ‘‘ Xylolin,”’ and they are stated to 

have firmly established themselves in 
the textile industry, competing chiefly 
with jute yarns. 


A considerable refinement in pro- 
duction has been aimed at in the two 
sroups of inventions about to be 
Peed nmdlon ter described, for which the starting 
twisting paper-strips. point is not a finished paper, but the 
_@ carries the con- wel in the unfinished condition in 
tinuous length of paper i ay : 
of 2—3 mm. width: which it 1s delivered from the press 
EEO CS rolls of the paper machine. 
erat Scie nis (b) The Kellner-Turk system is the 

consolidated result of the inventive 
work of the late Carl Kellner, of Hallein—a well-known 
pioneer of the wood pulp industry—and of G. Turk, of 
Bad Gastein. The main patents are those of 1891 
(D. R. P.-78601) and 1892. (. R.. P.. 79272) “andthe 
claims are similar, the former indicating the formation of a 
pulp-sliver by taking moist paper strips as delivered from 
a cylinder paper machine, and subjecting them whilst still 


WOOD PULP AND THE TEXTILE INDUSTRIES = 223 


on the cylinder wire to a rubbing and rolling treatment by 
which they are rounded and consolidated; the latter patent 
indicates the same general plan of manufacture, but the 
rolling of the strips takes place after they have left the 
machine wire. ‘The production of the paper or pulp strips 
is not patented. ‘This 1s effected by the special construction 
of the wire cloth of the paper-making cylinder, which is an 
alteration of impervious brass strips with the ordinary 
60— 70-inch mesh wire cloth; the pulp is deposited 
on the latter only. These patents were acquired in 1900 
by the Patentspinnerei A.G., in Altdamm, Stettin, in whose 
hands the process was further developed in the direction of 
the Turk patent. 

The main feature of the treatment of the strips is the 
process of conversion from the flat to the cylindrical form, 
under which there is an incidental consolidation of the 
fibrous aggregate. This effect is produced by passing the 
strips through a special apparatus, the principle of which 
may be traced to an invention of O. Schimmel & Co., 
Chemnitz, described in the German patent 76126, above 
cited. ‘The invention was in its inception applied to the 
‘“‘lap’’ of dry-carded short fibre as delivered from a textile 
carding machine. The lap delivered at the full breadth of 
the card is received between a pair of rollers which divide 
it by a peripheral cutting arrangement into narrow strips, 
which pass forward to the rolling apparatus. This consists 
of an upper and under endless band of leather in close 
contact, disposed for motion in the horizontal plane, each 
round a pair of rollers moving in geared connection. The 
rotation of these rollers carries forward the now divided 
strips, but an alternating movement in the direction at 


’ 


224 WOOD PULP AND ITS USES 


right angles is communicated to the leather bands by 
eccentrics, and this movement is in turn communicated to 
the strips as they travel forward, under which they are 
continuously rubbed and rolled into cylindrical form. They 


©. 6. © Gy. 


1 ‘4 
1 4 
| | A 
I ; A 
” P 
\ i / a 
| ! Z Ha 
! ag 
! : a 
a 
1 1 ‘4, 
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1 1 da 
1 if 4 
! | fe) @)~ ~ 
1 
| a 
\ 1 | | 
ene # La) ras Be 
| H 
. sie Rod wl} 
i eae ( y ee 
ED i Sey ia Cigaae} 
: eae 
E Sa SS — Re SScem Aa = 
as eae eee ae Q 
Ze <2 os ee Sed EE 
Spee nae Sees) ea=2 = Fy 
ia ee pees bitsoe | 
Skt pS atsv) acd 4, 
Un i, ) Nil Ecc asd Bs | 
Oak ies || 
ZZ Hi Ws 1 oe OH iS ZZ . = _ = =a 


Fic. 25.—Machine for rolling flat strips of prepared short fibre 
(sliver). The ‘lap’ is taken from the card P, sub-divided into 
strips in passing R R, rolled at N N, and delivered into cylin- 
drical boxes or cans, TT. (O. Schimmel, D. R. P. 76126.) 

are then suitably laid down in receivers, to be transported 
to the spinning or twisting frames (see Fig. 25). 

On the Kellner-Turk system, as applied to the wet pulp 
strips, a similar apparatus and process succeeds the press- 
rolls of the paper machine. ‘The endless bands of the 
rubbing and condensing rollers are in this case made of 


indiarubber. 


WOOD PULP AND THE TEXTILE INDUSTRIES) 225 


The third operation, that of spinning or twisting, is 
carried out on the still moist thread. There are various 
devices employed in the textile industry for conferring the 
high degree of twist which characterises the textile yarns 
in their final forms; the same principles and forms of 
machine are pressed into the service of the paper-pulp- 
spinner. The twisting is mostly carried out on “ Ringzwirn- 
maschinen,” ring-spindle machines, i.e., frames carrying 
60—70 spindles on the side. In making weft yarns, 
the delivery of the spun yarn is varied so that it may 
be wound directly into cops, or on to tubes placed over 
the spindles. There are two limitations to the efficiency 
of this system; one is in the mode of making the pulp 
strips on a cylinder machine. The alternative process and 
machine, based on the flat-running Fourdrinier wire, with 
its much higher productive efficiency, is adopted by them 
as the basis of the competing system which we shall next 
describe. The contrast of these two methods of converting 
beaten pulp into paper is well set forth in C. Hofman’s 
Handbuch der Papierfabrikation, ed. 1897, page 858. 

The second limitation of efficiency—that is, in output and 
therefore economic production—is in the speed of the 
machine and process of rounding and consolidating the 
strips. Taking 12—15 m. per minute as the speed of 
running, a machine of 80 spindles will produce in length 
from, 12° 80°x< 60 x 24 — 1,382°400' m: to 15 ‘x 80 x 
60 X 24 = 1,728,000 m. per diem: these lengths represent 
460 to 576 kilos. of a No. 3 yarn, or 115 to 144 kg. of a 
No. 12 yarn. In actual working, allowance has to be made 
for unavoidable breaks and stoppages, and the output is 
- taken at 30 per cent. less than these figures. It may be noted 
W.P. Q 


226 WOOD PULP AND ITS USES 


that a beating engine (Hollander) of 160 to 200 keg. 
capacity (dry pulp), dealing with four charges in the twenty- 
four hours, would feed two of such special machines. 

In summing up his notice of this system, Prof. Pfuhl 
expresses himself as follows (page 33) :—‘“‘It is probable 
that a number of circumstances, in addition to the not very 
satisfactory output of the sliver machine, have contributed 
to the present position (end of 1906) of the system, which 
is that after many years of existence, as indicated by the 
dates of the patents, 1f remains without industrial extension.” 

In connection with the development of the Kellner-Turk 
process, a number of patents have been taken by Leinweber, 
which have been acquired by the Altdamm Company. These 
inventions have reference to details which are found to be 
essential factors of economic production, such as the sub- 
division of the web of pulp into small strips (D.R.P. 140011). 
The mode of distributing these to the further operations 
(140,666) a further patent (140012) has reference to the 
rounding of the strips to a sliver by causing them to pass 
through a funnel, the tube of which is of spiral or other 
special construction, this treatment immediately preceding 
the spinning or twisting. 

System of R. Kron. ‘‘ Silvalin” yarns. 

It will have been evident during this discussion that 
wood-pulp ‘‘ spinning” is a hybrid process: a cross adapta- 
tion of well-known paper making and textile methods to 
the production of a particular type of fabric, and involving 
in a very special sense the question of cost of production. 
It may be noted in illustration of this point that while 
papers and staple textiles are produced and sold under a 
very wide range of costs and prices, the new industry in 


WOOD PULP AND THE TEXTILE INDUSTRIES 227 


the hybrid products depends mainly upon cost of production. 
The system which consolidates the inventions of Messrs. 
Kron claims important progress in this essential element of 
success. In the first place, the production of the original 
pulp-strips is “‘intensified” by employing the ordinary 
Fourdrinier machine at its full width, the web being sub- 
divided into narrow strips by an arrangement for projecting 
jets of water upon the web at such distances that the web 
is divided into 100—500 strips per metre. The separation 
of the strips is, however, not thus completed; they are 
wound up on a roll of the full width, and are afterwards 
separated and detached as discs. It is based upon the 
following patents, of which the subject-matter indicates the 
essence of the several inventions :— | 
I. Main patent (K. 23200 vii/76c). A process for twisting 
or spinning the cellulose (pulp) directly from pulp-rolls. 
(a) Addition-patent I. (KX. 23887 vii/76c) for winding up 
the wet-web at the breadth of the machine to be after- 
wards divided in pulp-dises of suitable narrow width, 
(b) Addition-patent II. (K. 23926, vii/76c). Improve- 
ments in the manufacture of pulp-rolls in a moist 
but coherent state. 
II. Main patent (K. 25168, vii/76c). Process and 
apparatus for winding up moist strips of paper pulp, etc. 
III. Main patent (K. 25043). Process and apparatus for 
sub-dividing a web of pulp (as on the wet end of a paper 
machine) into strips. 
IV. Main patent (K. 26001). Apparatus for direct 
delivery of moist pulp strips. 
V. Main patent (K. 25036). Spinning machine for 
preparation of detachable cops. 
Q 2 


228 WOOD PULP AND ITS USES 


The succession of operations in the Kron system is as 
follows :— 

1. The formation of the web on the Fourdrinier wire ; 
its sub-division into strips by the impact of jets of water 
for the number of strips required to be formed. 

2. The pulp-strips are subjected to the action of press- 
rolls for the gradual removal of water and progressive 
solidification of the fibrous aggregate; it is then further 
dried by heat on a steam-heated cylinder ; and then wound 
up in what is termed a magazine roll, which thus holds a 
series of discs in close contact. These are detached as 
required for the further operation of twisting, and are 
disposed for winding off in a horizontal or inclined position 
beneath the spindles. | 

8. The winding off and twisting involves the passage 
through the machine which is the subject-matter of patent 
No. 4 (ante) from which the strips are delivered continuously 
to the spindles. These have a speed of 3,000 to 8,000 
revolutions per minute, with the sliver travelling at 8 to 16 
metres per minute, according to the size of the yer and 
the degree of twist required. 

The following table of results of tests of tenacity and 
‘elasticity’ more particularly illustrates the technical 
features of the wood-pulp “‘ spinning” systems :— 


Metrical count. Breaking strain Extensibility 


in terms of per cent. 
breaking length. 
Silvalin strips (dry) 2,891 2,390 3°06 
satay ars. : 2,900 4,810 6°44 
Altdamm (Tiirk) aes . 18,158 4,170 2°84 
Strips rounded (sliver) . 8,222 5,014 2°24 
4 : 8,408 5,187 Phas 


Finished yan  . . 12,100 6,413 3-06 


WOOD PULP AND THE TEXTILE INDUSTRIES) 229 


From his extended investigations of these products Prof. 
Pfuhl concludes that this class of yarns made from pure 
wood-cellulose have a mean breaking length of 5 to 7 km. 
with an extensibility of 6 to 7 per cent.; and these constants 
define a textile quality sufficiently high for their utilisation 
under the ordinary conditions of wearing, both as warp and 
weft. The warps of wood-pulp yarns require no previous 
“dressing” or sizing. The finished fabrics, it may be 
mentioned, have about one-half the strength of jute fabrics 
of the same make and weight. In regard to the conditions 
of utilisation of such fabrics, it is to be noted that, when 
wetted, they lose their tensile quality entirely ; and although 
they regain their strength in drying, it is evident that the 
defect in question is a serious limitation of their utility. 

(b) Cost of Production of Silvalin Yarns.—The estimates 
of Prof. Pfuhl are based upon a daily output of 6,000 kg. 
or 1,800 tons per annum, involving 2,160 spindles running 
eleven hours; the corresponding production of sliver-strips 
running continuously, 2.e., twenty to twenty-four hours per 
day. In the estimates, the production of a No. 3 (metrical) 
yarn is considered. The capital outlay is summarised as 
follows :— 


Marks. 
Site and land, 15,000 kr.... es Lo SSI 
Buildings, 2,000 mr., ete. a Aud LOO 
Machinery and plant... OF ... 809,500 
Business capital ... ee ie ... 126,800 
523,000 


These represent an annual charge of about 36,000 m. and 
adding salaries the establishment represents a charge of 


230 WOOD PULP AND ITS USES 


56,807 m. per annum. Wages are estimated at 60,320 m., 
and coal (at 20 m.) 48,160, adding for lighting, packing, etc., 
41,000 m. The total annual charge is 201,287 m. This 
on the basis above set forth gives a cost of production per 
ton of 111°88 marks. Adding 20 marks for one patent 
licence, we have a total cost of 181°83 marks. Comparing 
these costs with those of spinning jute to yarn of the same 
count, which was estimated at 100 to 120 m. under similar 
conditions, it is seen that they are some 10 to 20 per cent. 
higher. The respective raw materials have now to be 
brought into account, viz., sulphite cellulose at 15 to 18 m. 
per 100 kg., and jute at £10 to £14 perton. The final 
comparison is made in the following terms :— | 


Marks for 100 kilos. 
Jute warp yarn, No. 6... 34 43 
Jute weft yarn, No. 5, 4 31 39 
Silvalin yarn, No.5, 5... 28 32 


Total cost of 
production 


Physical Properties and Application of Wood-pulp Yarns 
and Fabrics.—It has already been indicated, and is, in fact, 
more or less self-evident that wood-pulp yarns are limited 
in their utility. In measuring the utility a number of 
general principles have to be taken into account as well as 
the practices and conventions of the textile industry which 
follow fromthem. The numerical basis of measurement or 
weight 
length 
in the textile industry takes a number of conventional forms. 
The trade in coarse yarns which alone come into considera- 


the ‘counts of yarn” is the relationship, which 


tion here, is mainly concerned with flax, hemp and jute or 
bast fibre yarns, and low grades of cottons. Thus we have 


WOOD PULP AND THE TEXTILE INDUSTRIES 231 


the English units or yarn numbers for bast fibre yarns = 
the number of leas (of 800 yards) in the pound; for cottons 
the number of hanks (of 840 yards) in the pound. The 
jute trade (Dundee) takes an inverse measure in terms of 
the “‘ spindle” of 14,400 yards, the number of pounds in 
this length being the yarn number. For wood-pulp yarns 
the simpler metrical numeration obtains, viz., the number 
of metres (unit of length) to the gram (unit of weight). 
The following table, of the metrical yarn numbers and 
their equivalent in the conventional units will be found 
useful. 


Table of equivalent yarn ‘‘ numbers” or WEIRD 
length 
description compared with metrical counts. 
Metrical counts: Cottoncount: Flax counts: Jute counts : 
metres per n. (840) yds. n. (300) yds. lbs. per 
1 grm. per lb. per lb. 14,400 yds. 
1°0 et UO: O0 Lares. 1G 545i ee cs ee ORO 
GU oiete. 1°0 Hee 2BOO Mw @.. tee Lie 
O:O05ees.. OOS (anaes 1:0 tee to 
29°0 cee CA ee 450) mt 1°0 


The strength or “tenacity” of yarns is determined as a 
breaking-strain, but usually expressed as a breaking-length, 
that is, the length of the breaking-weight of the yarn itself. 
This is comparable at once with the sectional breaking- 
strain usually applied to solid substances. For where L 
expresses breaking-length, s specific gravity, and k the 
breaking-strain per 1 mm. of sectional area, LZ X s = k. 

Breaking-Length.—lt is an expression which eliminates 
two of the three dimensions, that is, it is independent of 
the sizes of yarns or threads, as of the thickness or width 


232 WOOD PULP AND ITS USES 


of fabrics such as paper produced in sheet or web. It will 
be noted as a conventional expression, but of very great 
“convenience,” and gives a comprehensive or aggregate 
expression of tensile quality, and thus is applicable to the 
most diverse substances and in their most varied form. 

Fracture of a textile yarn or paper is accompanied 
always by elongation under the strain; this of course is a 
certain measure of true elasticity. The latter would be 
defined as the amount of .extension of which the fabric is 
capable, with the condition of reverting to its former dimen- 
sions when the strain is removed. This quality, however, - 
is seldom defined or tested in textile fabrics. 

Extensibility is usually expressed as the total percentage 
elongation sustained at or under the breaking-strain. 

The following table of these quantities applies to the most 
important textiles. 


Breaking Length. 
Kilometres. Elasticity. 
¢ Cotton yarns a .. 13—14 3°97 
Ramie yarns - .. 11—12 0-S—1°'8 
Flax yarns, wet spinning.. 12°4—19°5 1:1—1°8 


Mean averages for 
ean averag Flax and tow yarns, dry 


Commercial eas 2 
spinning .. a .. 11:8—12°4 2°5—3°7 
Products. Jute yarns + = e ao 2°0 
Lustra cellulose average .. 12:0 2°0 


Artificial silks, extremes.. 8°0—14:0 7:0—18°0 


The mechanical properties of papers are expressed in the 
same terms, and it is interesting to compare the range of 
numbers for the highest classes of papers :— 


Breaking Length. Elongation. 
Metres. Per cent. 


Rag papers, Manila papers and 
wood pulp papers (air dry) ... 4,000—8,000 ... 3°8 


It is evident from these numbers that the shorter units 


WOOD PULP AND THE TEXTILE INDUSTRIES 233 


common to papers produce a texture approximating in 
mechanical properties to the lower grades of spun yarn. 
From the preceding exposé it would appear that inventors 
have endeavoured to overcome the unfitness of paper as 
such for textiles, or weaving uses, by changing the form and 
usual dimensions of the web of paper. The stages in the 
productions of a cylindrical product or yarn are (1) cutting, 
(2) rolling and (8) subjecting the cylindrical rolled strips to 
a twisting process whilst in a moist condition. The effects 
of these treatments in increasing the solidity and resistance 


of the agglomerates is shown by the following figures :— 
Breaking cee Elongation. 
km 


Per cent. 
Plane strips, dried emi ee el: 4: 17 ge Mee 
Rolled into cylindrical form... DLO see wee 
Rolled and twisted os Be 641 ... 3°06 


The following numbers have reference to wood-pulp yarns 
as industrially prepared : 
Silvalin (Kron process, 1908—4) : 


Menneome24 0 toctsme rn) ea 5498. "Gis 

Maximum observed oe e S50 4a LOD 

Minimum observed ae *. AS1 Oar ee 9 
Altdamm (Turk process, 1903—4) : 

Mean of 90 tests a i. IGE aes Ayal 

Maximum observed ee ae TEE Bs etna LEG 

Minimum observed ne cr O,ULO ee eee 


As a chemical individual wood cellulose differs but little 
from cotton cellulose ; and when only chemical relationships 
are involved, there is an obvious probability of the former 
being able to substitute cotton as a basis of manufacture. 


1 Km. is the contraction for kilometre. 


234 WOOD PULP AND ITS USES 


For such substitution there is always the inducement of 
relatively low market price. 


SPECIAL CELLULOSE INDUSTRIES. 


There are several important industries which have been 
developed upon the characteristic properties of derivatives 
of cotton cellulose. The modern industry of high explosives 
is based upon the nitric esters of cotton, which in certain 
cases are associated with the corresponding nitrates of 
glycerine. As shown in Chapter II. cotton can be nitrated, 
that is, combined with nitric acid by simple methods and 
without any evident structural change. The nitro-cotton, 
or gun cotton, has the external appearance .of ordinary 
cotton, but is harsher to the touch, and the addition of the 
large weight of 70 or 80 per cent. due to the combination 
with nitrate groups, causes minor structural changes which 
can be well observed under the microscope. 

The properties of gun cotton are primarily those 
associated with rapid or explosive combustion ; combination 
with the nitric groups introduces so much oxygen into the 
molecule that the new compound has all the elements or 
internal conditions for complete combustion, whereas 
ordinary combustion depends upon the gradual supply from 
without of atmospheric oxygen to the burning body. When 
eun cotton is fired, there is a rapid propagation of the. 
combustion, and when this takes place in an enclosed 
space detonation occurs, with rupture of any containing 
vessel, due to the enormous development of gas’ at high 
temperature. 


1 The products of explosion of the nitrate are represented by the 
equation 2 Co4H 3.05 (NO3H)i = 24°CG0 + 24 CO, + ity H, + 12 H,O 
+ 11 N, and the heat evolved is 2,200 calories per 1 gramme. 


WOOD PULP AND THE TEXTILE INDUSTRIES 238 


The cotton nitrates are soluble in a number of organic 
liquids in which they swell up and pass into homogeneous 
solution ; with limited proportion of such solvents, and 
mechanical means, the fibrous nitrates may be worked up 
into structureless plastic masses, which can be drawn or 
moulded into threads or rods, or rolled into sheet. It is an 
important discovery that glycerine or nitro-glycerine is a 
solvent of nitro-cellulose. Nitro-glycerine resembles nitro- 
cotton in fundamental combustibility, and is similarly a 
high or blasting explosive, even more powerful than nitro- 
cotton, owing to the somewhat higher relative proportion 
of oxygen. It sounds like a paradox that on bringing these 
two high explosives together a mixture results which has the 
properties of restrained combustion, or regulated explosion. 
These bodies worked together in suitable proportions pro- 
duce a plastic mass which can be drawn, as above stated, or 
shaped. When flame is communicated, there is a regulated 
combustion proceeding from the external layers to the 
* centre of the mass. Explosives of this order can, in 
fact, be used as propulsive explosives, that is for military 
ammunition; the ordinary forms are cordite, balistite, etc. 

It would appear to be possible to replace cotton for the 
manufacture of nitro-cotton by, the wood celluloses, but 
there are many reasons, partly of constitution, and partly 
having to do with the external characteristics or fibrous 
forms, which have prevented this from taking any deep 
root, and we can therefore hardly enter into the specialised 
technology of gun cotton and explosives as a development 
of wood-pulp industry. 

The same may also be said of the very important 
industry in articles known as celluloid, xylonite, etc. ‘This 


236 WOOD PULP AND ITS USES 


art and industry is based upon the plastic qualities of 
nitro cellulose when treated with suitable solvents, and ~ 
the plastic mass obtained by incorporating the fibrous 
nitrates with special solvents and completing the mixture 
to a homogeneous mass by means of mechanical appliances, 
can be shaped into any required form. There are particular 
reasons why this industry also has not availed itself of the 
supplies of wood cellulose of which the market value is 
approximately one-third that of the forms-.of cotton which 
are ordinarily used. 

These reasons, as previously indicated, are partly in the. 
relative inconvenience of handling the short fibres of the 
wood celluloses: and partly from the particular features of 
instability characterising compounds which are potentially 
self-destructive. Gun cottons and the lower nitrates of 
cotton are “unstable”? as originally produced owing to 
the presence of sulphuric acid residues in combination. 
These are eliminated by exhaustive washings and successive 
boilings with water. When so purified and “sterilised” 
they may be kept for prolonged periods without change. 

But other celluloses are constitutionally differentiated 
from the normal cotton cellulose, and contain a proportion 
of groups of less intrinsic stability: these nitrated to 
the same degree are correspondingly less stable, and liable 
to spontaneous decomposition. Hence a lower stability 
of the entire complex and unsuitability for these industrial 
uses. | 

Cellulose Acetates.—The highly combustible and explosive 
nature of the cellulose nitrates imports a considerable 
danger in the manufacture and use of celluloid or xylonite. 
An important use of the nitrates is for the manufacture of 


WOOD PULP AND THE TEXTILE INDUSTRIES) 237 


photographic films, and in ordinary use this has not led to 
any serious catastrophe. On the other hand, the film 
employed to carry the photographic picture in the kine- 
matograph, the picture being projected on to a screen by 
means of powerful illuminants, is a combination of risks, 
which has led to several disasters. It is a well-known 
objective of inventors to discover an efficient substitute 
for the nitrate. Cellulose acetate is an ester of cellulose 
which is a close analogue of the nitrate, is also soluble in 
organic solvents, and may be shaped in admixture with 
these in any desired way. The first serious attempts to 
prepare the cellulose acetate on the industrial scale date 
from 1890. It was found by ourselves that certain forms 
of cellulose can be brought into reaction with acetylating 
reagents in presence of zine acetate, and such process was 
carried out on an industrial scale. 

Further investigations of other chemists led to the 
observation that cellulose combines readily with acetic 
anhydride in presence of sulphuric acid relatively in 
small quantity, and taking part only in determining the 
main reaction. Such a process, the subject of a series of 
patents by Lederer (see p. 240), has led to considerable 
economy in the production of the acetate, and the matter is 
being industrially developed in one or two countries. The 
acetate film answering all the requirements of photographic 
use is still, however, in the embryo stage of development. 

Owing to the simplicity of the reaction and the relative 
inertness of acetyl groups, there is every reason why the 
wood celluloses should answer all requirements for this 
industry. The reaction is usually carried out with a 
mixture of glacial acetic acid and acetic anhydride in equal 


238 WOOD*PULP AND Ips sins 


proportions to which the calculated small quantity of 
sulphuric acid is added (Lederer); in contact with this 
reactive mixture, the celluloses are gradually and pro- 
eressively attacked and pass into solution: Low tempera- 
tures only are required, and 50°C. is the general maximum. 
The product is obtained asa highly viscous liquid, that is, a 
solution of the ester in the excess of the reactive mixture. 
The mixture is treated with water, which precipitates the 
ester, and, by suitable mechanical means, this is effected in 
a state of minute subdivision of the ester, so that it is easily 
washed. When dry it dissolves to bright solutions in its 
special solvents, which are chloroform, ethylene chlorides, 
acetic acid, phenol, etc. It is to be noted that these 
solvents present difficulties in use, and they are by no 
means so convenient as the solvents used for the nitrates. 
Variations of the process, however, have led to the pro- 
duction of acetates soluble in acetone, a solvent which is 
free from objection in use. 

An important question of cost necessarily enters as 
determining the extent of application of these bodies. 
Owing to the relative high price of acetic anhydride, and 
the necessity of using an excess of reaction mixture, the 
costs of acetate obtained as above. described is relatively 
high. In employing solvents, which are lost in the working 
of the acetate to particular forms, the cost is added to. 

Whereas cellulose nitrates can be bought in the open 
market at from 1s. to 2s. per lb., the acetates stand at a 
multiple of these figures, viz., 6s. to 9s. a lb. 

It is evident that such prices exclude applications save 
such as are relatively independent of cost. 

Another point to be noted in connection with these 


WOOD PULP AND THE TEXTILE INDUSTRIES 239 


acetates is that while the reaction is direct, and, in one 
sense, simple, there is no doubt that the use of acid 
catalysts brings about the breaking down of the cellulose 
ageregate by hydrolytic change, from which results a loss 
of structural properties. The acetates so produced and 
converted into continuous solids are relatively brittle. 

Processes which overcome these objections depend upon 
the use of neutral or saline catalysts, such as zine chloride. 
These appear to determine the ester reaction under con- 
ditions which do not involve hydrolysis or, at least, involve 
it to a much less extent. The products of such reactions 
are what may be considered the normal series of acetates. 
The reaction of cellulose with acetic anhydride in the 
presence of zinc chloride as catalyst, and glacial acetic acid 
as diluent can be observed through a remarkable series of 
eradations up to the extreme or maximum point. If cotton 
is used, or more particularly cotton yarn, it is easily seen 
that the lower acetates are formed without any sensible 
modification of the cellulose or yarn. Acetyl groups may 
be introduced into the cellulose molecule with an increase of 
weight up to 26 to 86 per cent., producing an acetylated 
derivative unchanged as to form, showing certain new 
properties in respect of lower attraction for atmospheric 
moisture, and for those colouring matters which dye cotton 
directly. When carried to higher stages, the further intro- 
duction of acetyl groups cause a notable swelling of the 
cellulose, and, finally, as the stage of tri-acetate is reached, 
the product passes into solution. This method of acetyla- 
tion is economical by reason of the fact that there is a very 
high utilisation of the acetic anhydride. 

A further point of economy arises in the application of 


240 WOOD PULP AND ITS USES 


the acetate, since for certain purposes the reaction mixture 
itself can be employed. This avoids the process of separa- 
tion of the ester, in which the solvent is lost, or so diluted 
as to have a much depreciated value; and, moreover, the 
separated ester requires again to be treated with solvents, 
which become an added cost. These difficulties, which 
appear of small magnitude, have effectually impeded the 
development of the applications of the product. A general 
bibliography on the subject since 1895 will indicate the 
directions in which specialists may inquire for evidence of 
the influence of these difficulties on the evolution of this 
cellulose ester. 


GENERAL BIBLIOGRAPHY OF CELLULOSE ACETATES. 


Original papers. 
Schutzenberger and Waudin. Comptes Rendus, 68, 814. 


Franchimont. Berl. Ber. 12, 2059. 
Cross and Bevan. Journ. Chem. Soc. (1890), 57, 1. 
1905 Cross, Bevan and Briggs. Berl. Ber., 38, 1859, 3531. 
Haeussermann. Chem. Ztg., 29, 667. 
1906 Ost. Zeitsch. Angew. Chem., 19, 993. 
1907 Berl. and Watson Smith. Berl. Ber., 40, 903. 
L003 aes a Journ. Soc. Chem. Ind., 534. 
F. Beltzer. Mer. Sci., 22, 648. 
Knoevenagel. Chem. Zeit., 32, 810. 
1895-1905 Cross and Bevan. “* Cellulose.” “¢ Researches on 
Cellulose,” I., ‘‘ Researches on 


Cellulose,” II. 


The following patents. 


1894 Cross and Bevan. 
1900 Lederer. 


. 96761. 
~ 11749. 


Ct et bt be 
ih Ost toed 


1902 Landsberg. . 4886. 
», Lederer. . 7088. 
} eesti. . P. 708457. 


WOOD PULP AND THE TEXTILE INDUSTRIES 241 


Miles. 
Farbenf. Elberfeld. 


Balston and Briggs. 

F. Rayer & Co. 

Lederer. 

Badische, A. 8. F. 

Miles. 

Fabr. Prod. Chim. Flora. 
Akt. Ges. f. Anilin. 
Farbenf. Elberfeld. 
Corti. 

Lederer. 


F. Bayer & Co. 
Knoll. 

Badische, A. 8. F. 
Lederer. 

Fischer. 

Knoll. 


Benne. 

Soc. Anon. Explosifs. 
Lederer. 

Knoll. 


Donnersmarck, K. A. W. 


9) 
Lederer. 


aq 


HAC HG OHO ROR eR dda ee 


Hat nett th PWN Etter t thon aomn 


P, 733729. 
P, 734123. 
P. 738533. 
10243. 
7346. 
Pan b40 bl 


. 347906. 


19330. 
9998. 

1939; F. P. 362721, 368738. 
P. 809938. 

P. 816229. 


. 19107, 26502. 
. 368766, 371357. 


371447. 
369123. 


. P. 373994, 812098. 


3108. 
374370. 


ee 290 

. 2026, 2026A, 2026B. 
. 373994. 

. 383636. 

. P. 210519. 

. 385179. 

ts 9020933 

p dey tse N Og ey 


7743. 


. P. 922340. 
. 400682. 


ES 11625, 


The derivatives above described are themselves esters or 
compounds of cellulose and acid groups, and are treated or 
manipulated as such. Thus, the solutions of both the 
nitrate and acetate can be drawn or spun to a thread, 
which, when sufficiently fine, is an artificial silk. The 
nitrate is the basis of the earliest, and still very successful, 


W.P. 


R 


242 WOOD PULP AND ITS USES 


method of producing these artificial textiles, nitro-cellulose 
is only a stage in a cycle of industrial operations. The 
nitrate is readily denitrated, that is, its nitro groups may be 
removed with regeneration of cellulose. The earlier forms 
of artificial silks were not so treated, or, at least, only 
partially denitrated, and therefore were necessarily highly 
combustible, if not explosive. This property very con- 
siderably prejudiced the earlier attempts at utilising them : 
this form has, however, given way to the denitrated or 
cellulose product, which is now an ordinary staple textile. 
The acetate in the form of thread or artificial silk could be 
used as such, as it is not more combustible than ordinary 
cotton. It is a product, however, that is still only an 
industrial curiosity, and has not taken any prominent 
position, probably owing to the cost of production of the 
original acetate which, for the reasons given, is necessarily 
high. A further difficulty in the same direction is the 
added cost of redissolving the products in solvents, which 
are lost during the spinning process. ‘There appears to be, 
however, a prospect of producing a thread to compete with 
the artificial silks already established, by spinning or draw- 
ing the original reaction mixture in the case of the normal 
series of acetates. 

We have already described a peculiar compound of cellu- 
lose, which resembles the above in being formed by com- 
bination of cellulose with acid groups; but the compound 
is soluble only in alkaline liquids, and, moreover, is” 
unstable, that is, decomposes spontaneously with reforma- 
tion of cellulose. This compound is the sulpho-carbonate, 
or xanthogenic ester of cellulose, generally known as 
‘“‘Viscose.”” This compound was described briefly in an 


WOOD PULP AND THE TEXTILE INDUSTRIES 243 


early chapter, and its capabilities of regeneration in struc- 
tural modifications were indicated. Viscose has been used 
in a number of industrial applications, all of which depend 
upon this essential property. (1) In thread or yarn, it is 
an artificial silk. (2) In plane or sheet form it is a 
transparent film. (8) Solidified in masses it is a solid, 
which, when dried, can be shaped or turned in the lathe to 
any required form. The cellulose can also be mixed with 
solid bodies in preparing mixed agglomerates in which the 
structural qualities of the cellulose as the binding or 
agelomerating medium assert themselves, even when 
diluted with large proportions of foreign inert matters. 
(4) In less definite forms, but exerting the same technical 
effects, viscose is used in sizing paper and textiles, and for 
various other applications. 

For the general reasons above stated these industries are 
not necessarily connected with wood pulps, since they are 
more generally applications of cellulose, As a matter of 
fact, however, the wood pulps are a most convenient form 
of cellulose for the manufacture of viscose, and we may 
therefore give a few particulars in elucidation of these 
newer developments. 

The first stage in the “‘ viscose process”’ is the conversion 
of the cellulose into alkali cellulose by treatment with 
caustic soda solution at mercerising strength (15°0O—20°0 
per cent. NaOH). 

The limits of composition of this product are 

Per cent. 

Cellulose . sae! i : 25—30 
Caustic soda (NaOH) : : 12°5—15. 
Water. : : ¢ : 62°5—55 
R 2 


244 WOOD PULP AND ITS USES 


There are two methods of treating the wood pulp (cellu- 
lose) with the alkaline lye. The first is to reduce the wood 
pulp in a kollergang with sufficient water to bring about the 
disintegration of the sheets, and then add the calculated 
quantity of caustic soda dissolved in such a quantity of 
water as to produce a mixture of the above composition. 

The second method is to steep the sheets in excess of a 
lye of 17°5 per cent. NaOH, lift, drain from the excess, 
press to a calculated weight, and then grind in a kollergang 
or mixer to secure even incorporation of the mercerising 
reagent with the cellulose. 

The alkali-cellulose is a voluminous semi-dry mass 
resembling bread-crumbs in appearance. It can be stored 
in masses without change of composition by drainage. 

The alkali-cellulose is protected during storage from 
access of atmospheric air—that is from the action of 
atmospheric carbonic acid. 

The second stage in the process is the reaction of the 
alkali-cellulose with carbon bisulphide. This takes place 
spontaneously at ordinary temperature. It is important to 
carry out the reaction in a closed vessel to prevent loss of 
the very volatile bisulphide. The vessel ordinarily used is 
of the form and construction of a churn. In dealing with 
large masses it is found of advantage to replace the simple 
barrel or cylinder by a vessel of hexagonal or octagonal 
form. The charge of alkali-cellulose having been intro- 
duced, the quantity of bisulphide is poured upon the mass, 
the vessel closed at the man-hole and slowly rotated, to 
secure even admixture and distribution of the contents. 

The reaction is attended with a rise of temperature of 3 
to 7°C. according to the mass, initial temperature and other 


WOOD PULP AND THE TEXTILE INDUSTRIES) 245 


conditions of reaction. The mass changes in colour to 
yellow, and the action is arrested at the moment that it 
begins to lose its voluminous free condition. 

The completed product tends to agglomerate, and for the 
purpose of making a solution it is important that this should 
be stirred into water before the stage of agglomeration is 

“reached. 

There are in fact two ways of working up the xanthate: 
the first is by the action of water to a solution of 10 to 12 
per cent. cellulose strength, the second, the agglomeration 
is completed by the action of heavy masticating rollers, 
such as are used in the manipulation of indiarubber. 

The latter method is, however, only used in connection 
with the making of solids which are shaped into cylindrical 
form as a stage in the preparation of the solids known as 
viscoid or viscolith. 

The viscose solution is the starting point for the prepara- 
tion of artificial silk. For this industry the crude solution 
is subjected to filtration which requires to be of a very 
searching kind. In spinning or drawing the silk the 
solution has to pass through orifices of fine dimensions, 0°1 
to 0°15 of a millimetre, and hence it is important to 
eliminate all residues of insoluble matter. 

The xanthate or soda salt of cellulose xanthogenic acid is 
the basis of viscose. It is accompanied by by-products of 
the original reaction and moreover, as it tends to spon- 
taneous decomposition by interaction of the alkali with the 
sulpho-carbonic residues in combination with the cellulose, 
there is an accumulation of these by-products at the expense 
of the xanthates, which hold a steadily diminishing pro- 
portion of the characteristic group. The spontaneously 


246 WOOD PULP AND ITS USES 


diminishing ratio of these groups to the cellulose is attended 
by diminishing solubility of the cellulose complex. 

Further, the by-products are soda salts of the carbonic and 
sulpho-carbonic series, and are precipitants of: the cellulose 
compound. In both directions therefore there is a tendency 
for the viscose to revert to the solid state. 

A solidified viscose is a coagulated xanthate, and may be 
washed in water, and then redissolved in caustic soda 
solution. 

The final stage in the reversion is cellulose itself, which 
is reached only after prolonged periods at ordinary tempera- 
tures. 

These phenomena are made use of in several of the 
applications of viscose, as 1n the engine sizing of paper 
and the sizing and finishing of textiles. The decomposition 
is hastened by the interaction of the soda salts with salts 
of zinc or magnesia, and these are employed in the process 
of paper sizing. 

Another characteristic decomposition is that determined 
by salts of ammonia. Viscose in contact with sulphate of 
ammonia in solution interacts quantitatively; the soda is 
converted into sulphate and is replaced by ammonia (base) 
in both the by-products and the xanthate. These ammonia 
compounds are extremely unstable, and therefore there is a 
very rapid decomposition of the xanthate to cellulose 
(hydrate). ‘This reaction is the basis of one of the methods 
of spinning or drawing to artificial silk. 

Another method which also fulfils requirements of the 
spinning process, is that of treatment with acids, which 
bring about a still more rapid decomposition. 

Notwithstanding the rapidity of action the cellulose 


WOOD PULP AND THE TEXTILE INDUSTRIES 247 


hydrate adapts itself perfectly, and shows the same con- 
tinuity of substance and resistant quality as in the case of 
the saline baths. 

In regard to mechanical methods, these are two, in 
principle and detail. 1. The solution is projected from a 
fine glass tube: each individual thread is thus formed apart, 
and a certain number of these are united into a compound 
thread by passing through a glass loop in the coagulating 
or decomposing bath. 

The compound thread with its 14 to 18 elements is 
manipulated in the untwisted state, in the first instance ; at 
a later stage, as a special operation, it receives the twist of 
100 to 200 per metre. 

An ingenious method of combining these operations is 
the centrifugal spinning box of Stearn and Topham. 

This is a box of special construction rotating at a high 
rate of speed on a vertical axis. In this case the compound 
thread is directly produced in the coagulating bath by 
projecting the viscose through a plane cap or nozzle of 
platinum perforated with 14 to 18 holes. Each hole con- 
tributes a thread, and these are drawn forward in the 
coagulating bath as a compound thread, which ascends and 
is taken vertically up and down over a glass roller to fall 
into a funnel which communicates with the rotating box. 
The centrifugal motion has the effect of drawing the thread 
forward, twisting it, and laying it peripherally in the box 
as a hollow or annular cocoon, 

The hydrated thread in this “‘cake”’ form is removed 
from the box at intervals, re-wound into skeins and further 
manipulated for purification of the cellulose. 

The industrial applications of viscose necessarily involve 


248 WOOD) PULP ANDAITS USkKs 


a multiplicity of detail both chemical and mechanical. 
Chemically, the product is difficult to handle by reason of 
its alkalinity and the large proportion of derivative sulphur 
containing groups which are characteristic of the product 
and by-products. 

When these are decomposed, the. products are sul- 
phuretted hydrogen and other odorous derivatives. 

When the decomposition takes place spontaneously, the 
alkaline reaction being maintained, the products are carbon 
bisulphide and traces of other sulphur derivatives. 

The mechanical difficulties of handling viscose are largely 
a question of materials, that is, of materials having the 
power of resisting the attack of the associated products 
whether in the original condition or under the condition of 
decomposition by the reagents above indicated. 

It would be outside the scope of this work to deal with 
these matters in detail. 

A large number of inventions dealing with these methods 
and details have grouped themselves around the original 
invention, which dates from 1892. These inventions and 
developments are so numerous that they form the subject 
of a monograph of 127 pages, with 88 pages additional, 
devoted to the patent literature. We give the title of this 
work in full: ‘‘ Die Viscose—ihre Herstellung, Higen- 
schaften, and Anwendung,” von Dr. B. M. Margosches in 
Brunn. Leipzig. LL. A. Klepzig. 

This monograph is extensive, and in fact complete, and 
it is therefore unnecessary to duplicate this contribution to 
technical literature. 

In the course of discussions in this and preceding sections, 
we have not dealt directly with the commercial aspects of 


WOOD PULP AND THE TEXTILE INDUSTRIES 249 


the wood pulp industries nor with the subject of their 
money or selling values. These involve questions of minute 
detail, anda special aspect of these industries outside the 
scope of the present work. 

But we may deal in a very broad and general way with 
these values, as an illustration of an important principle of 
technology, that is, the appreciation of value of a raw 
material worked up by the agencies of chemical reagents, 
coal and steam, and manual labour, into a finished 
manufactured product. 

The German language, we may note in passing, provides 
the apt term ‘“‘ vered(e)lung”’ which means literally 
“ennobling,” for this process of adding value to raw 
materials and the special term connotes the general idea and 
aim of manufacturing industry. We have to borrow a 
Latin equivalent, and this suggests that the idea of 
‘appreciation ” 1s somewhat of an exotic. 

However the associated ideas may be expressed and 
assimilated the facts are equally striking and interesting, 
and in the case of the cellulose industries they may be stated 
in the form of an ascending scale of related values as 
follows:— 


(a) 1 cubic metre of wood weighs 400—500 kilos. 
and is worth in the forest, say ANB 
(b) Used as fuel it has a “burning” value, say O 6 O 
(c) As mechanical wood pulp it is worth, say . O 7 
(d) Treated by the bisulphite or alkali process 
it would yield 150 kilos. of pulp, say Se ES 
(e) Transformed into paper the pulp or cellulose 
is worth, say . : : : - ee SAR ANGS AS 


250 WOOD PULP AND ITS USES 


(f) Transformed into wood pulp yarn, it is 

worth, say  . 2 69a 
(g) Transformed into artificial “ilk or Iatre 

cellulose, it is worth, say+~ < » .) 9 See 


These figures cannot be stated more exactly, that is, 
represent actual selling values; but fractional variations 
would not affect the general scale of values which mounts in 
multiples from 1 to 50. Specialists are aware that these 
achievements in ‘“‘ veredlung’’ by no means exhaust the 
possibilities of cellulose technology and industry. 


1 This interesting industrial record we owe to Dr. O. Witt and Max 
Miller. 


CHAPTER XI 


SPECIMEN PAGES—VARIOUS TYPES OF PAPER 


Turs chapter embodies specimen sheets of paper selected 
as types, with a description of their characteristics. The 
selection is designed to bring out the position of wood 
pulps, in their various forms, as staple paper-making raw 
material. 

In establishing this position there have been, of course, 
the two elements of competition: first, technical effect ; 
and second, cost. 

As a result of the competition, the wood pulps have 
largely displaced cotton, jute and esparto. The general 
result of their introduction has been to cheapen production, 
with no sensible lowering of general quality. 

It is unnecessary again to point out that ground wood or 
“mechanical” wood pulp has many undesirable character- 
istics, and, of course, it is rigidly excluded from papers for 
documents of permanent value. 

But even this “Cinderella’’ fibre has proved of great 
practical importance and utility, in enabling papers to 
be produced at a cost commensurate with the enormous 
demand for cheap publications. 

The careful comparison of these papers, with attention 
to the full specification of characteristics printed on each 
sheet, will enable the reader to draw his own conclusions as 
to the extent to which wood has vindicated its present 
position as of first-rate importance. 


BIBLIOGRAPHY 


TITLE AND AUTHOR. 


Beitrage zur Kenntnis der Che- 
mische zusammensetzung des 
Fichtenholzes. . P. Klason. 
Berlin, 1911: Borntraeger. 

Cellulose, 1895. 

Researches on Cellulose, I., 1901. 

Researches on Cellulose, IT., 1906. 
Cross & Bevan. 

Chemistry of Papermaking. 
Griffin & Little. New York, 
1894: Lockwood. 

Die Chemie der Cellulose. 
G. Schwalbe. 
Borntraeger. 

Die Cellulose Fabrikation. 
Schubert. Berlin, 1906. 

Etudes sur les Fibres Végétales 
textiles. M. Vetillart. Paris, 
1876. . 


Carl. 
Berlin, 1910: 


Max 


Introduction to Vegetable Phy- 
siology. J. Reynolds Green. 
1900. 

Paper-maker’s Pocket Book. J. 
Beveridge. 

Papierprufung. Herzberg. 3rd 
edition. Berlin, 1906. 

Pflanzen Faser. Hugo Mueller. 
Reports Vienna Exhibition, 
1873. 


CHARACTER OF SUBJECT-MATTER. 


Theoretical investigation of con- 
stitution of pine wood. 


Systematic account of the chem- 
istry of cellulose and deriva- 
tives, and special accounts of 
researches to date. 

Modern account of wood pulp 
processes. 


A compilation on various works 
on cellulose. 


A practical text-book dealing with 
wood pulp processes. 

A standard book of reference on 
vegetable fibres, dealing with 
minute structure and correla- 
tion of microscopic charac- 
teristics with industrial uses. 

A standard text-book of plant 
physiology. 


Tabulated constants and numeri- 
cal statistics incidental to 
manufacturers. 


Original investigations on vege- 
table fibres. 


264 


TITLE AND AUTHOR. 


Plant Structures. Coulter. New 
York, 1900. 

Praktischer Handbuch der Papier- 
fabrikation. Hoffman. Berlin, 
1897. 

Technologie der Fabrikant. E. 
Kirchner. Biberach, 1905-7. 
The Paper Trade. A. D. Spicer. 

London, 1907. 

Die Viskose ihre Herstellung 
Eigenschaften und Anwen- 
dung. Leipsic, 1906. Mar- 


gosches. 


WOOD PULP AND ITS USES 


CHARACTER OF SUBJECT-MATTER. 


An excellent book, dealing with 
plant morphology. 
Thorough manufacturing details. 


Engineering details. 


Original collection of statistics. 


ARTICLES. 


‘* Paper’ in Spon’s Encylopedia of Useful Arts. 


“Cellulose,” ‘‘ Paper.” 


Thorpe’s Dictionary of Chemistry. 


J OURNALS. 


Papermaker. 
Papermaking. 


Paper Trade Review. 


Paper, Box, and Bag Maker. 


Paper Trade Journal. 
Berlin. 


Papierzeitung. 
Papier Fabrikant. 


Wochenblatt fuer Papierfabrikation. 


New York. 


Biberach. 


INDEX 


ee 


A. 


AcETATES of cellulose, 36, 48 
bibliography, 240 
cost of production, 238 
solvents, 238 
Aceto-sulphates of cellulose, 49 
Acid-sulphuric esters of cellulose, 
48 
Afforestation, 79—85 
Aleohol from waste 
liquor, 128 
Alkali-cellulose, 50 
Alkalis, action upon cellulose, 52 
sawdust, 199 


sulphite 


Angiosperms, 4 
Aniline sulphate, 114 
Annual rings, 19 
Aromatic bases, 70 
Artificial silk, 41 
Assimilating organs, 4 
tissue, 16 
Autoxidation, 29 


B. 


BARKING machine, 96 

Bast, 18 

Beating, 184 . 

Beech wood, 29 

Benzoates of cellulose, 86, 49 


Beveridge, 134 

Birdseye grain, 24 

Bisulphites, 58 

Bleaching of wood pulp, 147, 152, 
173, 174 

powder _ liquors, 
analysis, 147 
consumption, 
153—162 
effect of keep- 
ing, 148 

residual, 149 
strength, 147 

Board machines, 191, 192 

Box-making, 193 

Breaking length, 40 

Breast roll, 187 

Brown wood pulp, 109 

Burr, 24 

C. 


Catuuvs plate, 18 
Calorific value of wood, 27 
Cambium, 20 
Canadian Forestry Convention, 
82 
Castner-Kellner system, 175 
Cell, 9 
Celluloid, 235 
Cellulose, 29 
acetates, 36, 48, 238, 240 


266 


Cellulose, 
acetates, bibliography, 240 
aceto-sulphates, 49 
acid-sulphuric esters, 48 
action of alkalis, 52 
benzoates, 86, 49 
compound, 55 
constitution, 46 
decomposition, 54 
denitration, 242 
double salts, 86 
esters, 36, 45, 47, 234, 242 
group, 90 
mixed esters, 50 
nitrates, 36, 234, 242 
oxidation, 52, 53 
relative values of different 
forms, 249 
solvents, 47 
special industries, 234 
Chemical wood pulp, 28, 120 
history, 91 
list of inventions, 28, 120 
Chlorine, 58, 116, 165 
Chromic acid, 538 
Claviez system, 221 
Cold ground pulp, 97 
Collateral bundles, 21 
Collenchyma, 16 
Colloids, 33 
Comparison of sulphite and soda 
wood papers, 185—140 
Composition of sulphate liquor, 


140 
waste — sulphite 


liquor, 124 
Compound celluloses, 55 
Concentrator, 143 
Conducting tissue, 13 
Constitution of cellulose, 46 
Cork, 15 
Cortex, 15 


INDEX 


Cost of afforestation, 83 
Couch roll, 187 

Cross and Bevan, 41 
Crystalloids, 33 


D. 


DENITRATION of cellulose, 242 

Densities of various woods, 25 

Destructive distillation, 54, 202 

Dextion, 125 

Dicotyledonous stem _ structure, 
18 

Dimethylparaphenylene diamine, 
70, 114 

Dorenfeldt, 126 


EK. 


Economica bleaching conditions, 
144 

Eibel system, 188 

Ekman and Fry, 94 

Elasticity, 40 

Electrical units, 1683—165 

Electrolytes, 34, 165 

Electrolytic bleaching, 162 

Epidermis, 15 

Exogenous stem, 19 

Explosives, 239 

Extensibility, 40 


ie 


FELTING, 187 

Ferments, action upon cellulose, 
53 

Fern, structural features, 3 

Ferric-ferricyanide, 68, 114 


INDEX 267 


Fibres, 11 

length of various, 215 
Films, 43 

photographic, 237 
Forestry, 78 
Fossil resins, 75 
Fourdrinier paper machine, 187 
Furfural, 55, 61 


Gs 


GELATINE, 33 
Ginning process, 219 
Grain, 22 

Grinder, 98 
Gun-cotton, 234 
Gymmnosperms, 4 


lak 


Haas and Oettel apparatus, 166 

Hardness of various woods, 26 

Hargreaves-Bird process, 175 

Heart wood, 20 

Hemicellulose, 56 

History of chemical pulp, 91 

mechanical pulp, 90 

Hoffmann, 124, 225 

Hollander, 185 

Hot ground pulp, 97 

Houghton, 92 

Humidity of atmosphere, effect 
upon various pulps, 213 

Hydriodic acid, action 
cellulose, 638 

Hydrobromic acid, action upon 
cellulose, 51 

Hydrochloric acid, action upon 
cellulose, 52 

Hydroxy furfurals, 70 

Hypochlorites, action upon cellu- 
lose, 52 
W.P. 


upon 


J. 


JORDAN refiner, 187 
Jute fibre, 29 
xanthogenic acid, 68 


Ke 


KELLNER-TURK system, 222 
Kirschner, 100—105 

Kraft papers, 134 

Kron system, 226 


ai 


LIGNIFICATION, 29 
Lignified vessels, 25 
Ligno-cellulose, 80, 56—64 
bleaching, 65—67 
esters, 65 
photochemical 
TL 
Lignone, 80, 57—64 
action of bisulphites, 58 
chlorine, 58, 116 
constitution, 66 
effect on chemical reactivity, 
68 
sulphonates, 65, 124 
Lignorosin, 127 
Lustra-cellulose, 42 


phenomena, 


M. 


MaGnesium hypochlorite, 166 
Manufacture of chemical wood 
pulp, 120 
mechanical wood, 
96 
Marshall refiner, 187 
Measurement of timber, equiva- 
lent table, 88 
Ss) 


268 


Mechanical tissue, 18, 16 
wood pulp, 27, 96 
determination in 
papers, 111—119 
manufacture, 96 
output under 
varying condi- 
tions, 100—105 
Medulla, 19 
Medullary rays, 19, 24 
Meristematic tissue, 20 
Mestome, 13 
Methoxyl, 63 
Methyl groups, percentage in 
various woods, 64 
Metrical yarn numbers, 231 
Micro-chemical reactions of fibres, 
113 
Microscopic analysis, 112 
Mixed esters of cellulose, 49, 50 
Monocotyledonous stem struc- 
ture, 21, 22 
Multiple effect evaporator, 1388 


Ne 


4 
‘‘ News”’ and Printings, 178 
mill, economy in work- 
ing, 180 
Newspaper, composition, 180 
improvements in 
manufacture, 183 
Nitrates of cellulose, 86 
Nitric acid, 60 


O. 


Osmasis, 34 
Oxalic acid, 200 
Oxidants, 52 
Oxycellulose, 53 


INDEX 


z, 


PapER pulp yarns, 220 
Para-abietic acid, 22 
Parenchyma, 12 
Patent Spinnerei, 228 
Pentosan, 62 
Permanganates, 
cellulose, 52 
Phenols, 69, 114 
Phloem, 18 
Phloro-glucinol, 69,114 
Photo-chemical phenomena, 71 
Photographie films, 237 
Photosynthesis, 6 
Physical properties of woods, 25 
Pinchot, 81 


action upon 


Pith, 19 
flecks, 25 
rays, 19 


Pollution of streams, 129 
Porion evaporator, 137 
Power, 181 

Printing papers, 70 

Producer gas from wood, 200 


Q. 


Quick cook process, 121 


R. 


Reactions of decomposition, 51 
Refiners, 187 

Relation of yarn to paper, 218 
Residual bleach liquors, 149 
Russell, 29, 71 


SAP wood, 20 
Saponification, 48 
Sawdust uses, 199 


INDEX 


Schimmel, O., & Co., 223 
Schuckert’s electrolyser, 172 
Sclerenchyima, 16 
Screening, 105 
Secretionary products of plants, 
25 
Sheathing tissue, 16 
Siemens & Halske electrolyser, 
168 
Sieve tube, 18 
Silvalin yarns, 226 
Slowcook process, 122 
Soda process, 131 
recovery, 136 
Sodium hypochlorite, 163 
Solvents of cellulose, 47 
Sources of supply, 76 
Spermatophytes, 3 
Spinning of textile yarns, 217 
Starch, 82 
Steamed wood, 109 
Stele, 15 
Stem structure, contrast of 
monocoty! and dicotyl, 14 
Stereome, 13 
Strehlenert, 41 
Strength of various woods, 26 
wood pulp 
yarns, 228 
Sugars, 34 
Sulphate liquor, analysis, 140 
process, 189 
Sulphite liquor, 122 
process, 121 
Sulpho-carbonates, 39 
Sulphuric acid, 51 


Ate 


TEMPERLEY, 150 
Tenacity, 40 
Tensile strength, 40 


269 


Testing wood pulp for moisture, 
206 
Tetmayer, 26 
Textile industries, 215 
yarns from paper, 220 
Tilghman, 92 
Tintometer, 161 
Tower system of bleaching, 142 
Tracheex, 18 
Tracheids, 18 


ve 


VASCULAR tissue, 14 

Vessels, 11 

Viscose, 389, 48, 242—249 
spinning, 245—247 


W. 


WasHInG and finishing, 130 
Waste sulphite liquors, 123 
composition, 124 
sizing products, 125 
Wedge method of testing pulp, 
209 
Wet press machine, 108 
Wood, 18 
calorific value, 27 
composition, 120 
digestion in water, 109 
standards of measurement, 
85 
Wood pulp bleaching, 141 
boards, 190 
chemical, 28, 120 
list of inventions, 
95 
imports, 176 


270 


Wood pulp, mechanical, 27, 96, 
100—105, 111—119 
production in various 
countries, 77—79 
sources of supply, 76 
trees, 89 
yarns, 220 
cost of produc- 
tion, 229 
physical proper- 
ties, 280 
strength, 228 


BRADBURY, AGNEW & CO. LD. 


INDEX 


Wood waste, utilisation, 198 


wool, 199 
».G 
XANTHOGENIC ester of cellulose, 
39, 43, 
242, 2438 
jute, 68 


Xylem, 18 
Xylolin, 222 
Xylonite, 235 


PRINTERS LONDON AND TONBRIDGE. 


SPECIMEN PAPER. 


Nowl: 


Trade Description. 
Heavy Imitation Art. 46 lbs. Demy = 480 sheets. 
(Messrs. Spalding & Hodge.) 

Price 23d. per Ib. 


RESULTS OF TEST. 


WEIGHT OF REAM. 
Demy 174"’ x 224’ = 480 sheets 
Gramines per square metre 


THICKNESS. 
Single sheet 


STRENGTH. 
Tensile strength on strips 
15 mm. wide (Leunig’s machine) 
Machine direction Tcl lleyey, 
Cross direction 9°3 lbs. 
Mean tensile strength of paper 


BREAKING LENGTH 


BREAKING WEIGHT PER SQ. MM. OF 
SECTIONAL AREA 


Loss oF STRENGTH DUE TO FOLDING, 
On folding 4 times mean % loss 
On folding 12 times mean % loss 


BuRSTING STRAIN, 
Lbs. per square inch required 
Grammes per square centimetre 
ASH. 
Percentage of loading ... 


FIBROUS COMPOSITION, 
Esparto _... Ane 
Sulphite Wood 


“46 lbs. 


‘0058 ins. 


11°7 lbs. 


2269 yds. 


51-395 
65°0% 


24:0 lbs. 


30°4% 


80% 
20% 


171°1 gms. 


‘147 mm. 


5°32 Kilos. 
2073 Metres. 


2413 gms. 


1687 gms. 


VOLUME COMPOSITION. 


Grammes per C¢.Cc. 


Percentage composition 


by volume. 


Paper Fibre Ash Fibre 
1163 “809 354 53°9 


Ash Air space 
14°2 


| 31°9 


= 
ae 


aoe ee 


fT ahayV 


. ‘ 
bah oe 
Se: 


. 


Napier 


SPECIMEN Paper. NO. 3. 


Trade Description. 


Sulphite Printing. 21 1bs. Demy = 480 sheets. 
(Messrs. Lepard & Smith.) 
Price 24d. per lb. 


RESULTS OF TEST. 


WEIGHT OF RAAM. 
Demy 173” x 223” = 480 sheets 21 Ibs. 


Grammes per square metre ... 78°1 gms. 
THICKNESS. 

Single sheet “o Le .. ‘0033 ins. °*084 mm. 
STRENGTH. 


Tensile strength on strips 
15 mm. wide 


Machine direction 7-4 lbs. 
Cross direction 2p Dss 
Mean tensile strength of paper 5:0 lbs. 2°27 Kilos. 
BREAKING LENGTH .. ase ... 2125 yds. 1938 Metres 
BREAKING WEIGHT PER SQ. MM. OF 
SECTIONAL AREA ... : 1800 gms. 


Loss oF STRENGTH DUE TO FOLDING. 
On folding 4 times mean loss 34:0 °/, 
On folding 12 times mean loss 40-0 °/, 


BURSTING STRAIN. 
Lbs. per square inch required 9°5 lbs. 


Grammes per square centimetre 668 gms. 
ASH. 

Percentage of loading ... bao) DST 
FIBROUS COMPOSITION. 

Sulphite wood ... po 53 100 °/, 


VOLUME COMPOSITION. 
Percentage composition 
by volume. 


Grammes per €.c. 


Paper Fibre Ash Fibre Ash Air space 


929 725 “204 48°3 8°2 43°5 


SPECIMEN Paper. No. 4. 


Trade Description. 


Imitation Art. 22 lbs. Demy = 480 sheets. 
(Messrs. Lepard & Smiths, Ltd.) 
Price 28d. per lb. 


RESULTS OF TEST. 


WEIGHT OF REAM. . 
Demy 173” x 223” = 480 sheets 22 lbs. 


Grammes per square metre... 81°8 gms. 
THICKNESS. 

Single sheet “es a .. ‘0030 ins. °076mm. 
STRENGTH. 


Tensile strength on strips 
15 mm. wide (Leunig’s machine) 


Machine direction 9°4 lbs. 

Cross direction 4°7 lbs. 

Mean tensile strength of paper 7:1 lbs. 3°23 Kilos. 
BREAKING LENGTH .. aes .. 2880 yds. 2633 Metres. 
BREAKING WEIGHT PER SQ. MM. OF 

SECTIONAL AREA ... 2834 gms. 


Loss oF STRENGTH DUE TO FOLDING. 
On folding 4 times mean loss 549 °/, 
On folding 12 times mean loss 69:0 °/, 


BURSTING STRAIN. 
Lbs. per square inch required  15°1 lbs. 


Grammes per square centimetre 1055 gms. 
ASH. 

Percentage of loading .. She, eee 
Fiprous ComMposiTION. 

Esparto ... ies ond it 90 % 

Sulphite wood ... oe % LOM E 


VOLUME COMPOSITION. 


Percentage composition 


Gramm r ¢.e. 
BS, POPES by volume. 


Paper Fibre Ash Fibre Ash Air space 
1-076 816 ‘260 54°4 10°4 35°2 


SPECIMEN Paper. No. 5. 


Trade Description. 


Esparto Printing. 22 lbs. Demy = 480 sheets. 
(Messrs. Lepard & Smiths, Ltd.) 
Price 2Zd. per lb. 


RESULTS OF TEST. 


WeicHt oF REAM. 
Demy 173%” x 223’’ = 480 sheets 22 lbs. 


Grammes per square metre ..,. 81°8 gms. 
THICKNESS. 

Single sheet ae ae .. 0034ins. -*086 mm. 
STRENGTH. 


Tensile strength on strips 
15 mm. wide (Leunig’s machine) 


Machine direction 9°5 lbs. 

Cross direction Dro Lbs. 

Mean tensile strength of paper 7°4 Ibs. 3°37 kilos. 
BREAKING LENGTH ... =. ... 8002 yds. 2745 metres. 
BREAKING WEIGHT PER SQ. MM. OF 

SECTIONAL AREA ... : 2613 gms. 


Loss OF STRENGTH DUE TO FOLDING. 
On folding 4 times mean loss 324 °/, 
On folding 12 times mean loss 44°6 °/, 


BURSTING STRAIN. 
Lbs. per square inch required 17:2 lbs. 


Grammes per square centimetre 1198 gms. 
ASH. 

Percentage of loading ... sta DOSY fe 
FIBROUS COMPOSITION. 

Ksparto ... Bs a D4 80 °/, 

Sulphite wood ... hea ahs 20 Che 


VOLUME COMPOSITION. 


Grammies per ¢.¢. 


| Percentage composition 
by volume. 


Paper Fibre Ash Fibre 


Ash | Air space 
952 ‘790 “162 52°7 


6°5 | 40°8 


ae ig 


/ ’ Bi dig a 
‘ “4 “ ‘ ie ee ee Se 
= - ps ie A 9 AS Dyine tp tens’ ro 


ad Zz 4 
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; rs 

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Slee NY ey ; soe Cen) sit Ttee te OE =e 
' ; £ a wit he OURAN Biys, ie 


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f PEt te vay fu ny a rb Hz Wye tm / 


CLM, “Peres, 5 NW rie 
A as AM no aaa TTL ome 


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ah. dtl’ NGPA) Bele ey ona eee Te thre eee Ot eee sy a rw: 
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4 J aie - F 
is f , s * . x » j Pony #0’) : felt f bys ais 


SPECIMEN PAPER, 


No. 6. 


Trade Description. 


High-class Art Paper. 


41 lbs. Demy = 480 sheets. 


Prices on application to Messrs. C. Morgan & Co. 


RESULTS OF TEST. 


WEIGHT OF REAM. 
Demy 173"’ x 224’’ = 480 sheets 
Grammies per square metre 
THICKNESS, 
Single Sheet oid aS 
STRENGTH. 
Tensile strength on strips 
15 mm. wide (Leunig’s machine) 
Machine direction 13°8 lbs. 
Cross direction 74 Ibs. 
Mean tensile strength of paper 


BREAKING LENGTH ... es ote 


BREAKING WEIGHT PER SQ. MM. OF 
SECTIONAL AREA 


Loss OF STRENGTH DUE TO FOLDING. 
On folding 4 times mean % loss 
On folding 12 times mean % loss 


BURSTING STRAIN. 
Lbs per square inch required 
Grammes per square centimetre 
' ASH, ; 
Percentage of loading ... 


SIZING. 


Percentage of gelatine .., ase 
FIBROUS COMPOSITION. 

Esparto ... Zen wr ae 

Sulphite Wood ... ace be 


41 lbs. 


*0052 ins. 


10°6 lbs. 
2306 yds. 


49°1% 
63°2% 


23°3 lbs. 


29:0% 
5°43% 


45% 


55% 


152°5 gyms. 


132 mm. 


4°85 Kilos. 
2114 Metres. 


2488 gms. 


VOLUME COMPOSITION, 


Grammes per ¢.c¢. 


Percentage composition 


by volume. 


: irene Gela- 
Fibre | Ash tine 


063 


Paper 


1152 | °755 334 


Fibre | Ash 
50°3 | 13-4 


Gela- | Air 
tine | space 
4:7 31°6 


SPECIMEN PAPER. No. 7. 


Trade Description. 


Common Art Paper. 388 lbs. Demy = 480 sheets. 
(Messrs. Lepard & Smiths.) 
Price 23d. per lb. 


RESULTS OF TEST. 


WEIGHT OF REAM. 
Demy 173"’ x 224'’ = 480 sheets 38 lbs. 


Grammes per square metre ... 141°4 gms. 
THICKNESS. 

Single sheet San ee PeNOODS Mise 135 mm. 
STRENGTH. 


Tensile strength on strips 
15 mm. wide (Leunig’s machine) 
Machine direction 11°8 lbs. 


Cross direction 4°8 lbs. 

Mean tensile strength of paper 8°3 lbs, 3°76 Kilos. 
BREAKING LENGTH ... as ... 1950 yds. 1778 Metres. 
BREAKING WEIGHT PER SQ. MM. OF 

SECTIONAL AREA ... Gs 1858 gms. 


Loss OF STRENGTH DUE TO FOLDING. 
On folding 4 times mean % loss = 410% 
On folding 12timesmean %loss  48:2% 


BURSTING STRAIN. 
Lbs. per square inch required  18°2 lbs. 


Gramumies per square centimetre 1275 gms. 
ASH. 

Percentage of loading ... 3 28°3% 
SIZING. 

Percentage of gelatine... eS SOU 
FIBROUS COMPOSITION. 

Sulphite Wood .., 8 Ss 90% 

Mechanical Wood Suis a 10% 


VOLUME COMPOSITION, 


Percentage composition 
Grammes per ¢.c. by volume. 


ee 2 Gela- ; Gela- | Air 
Paper | Fibre | Ash ihe, Fibre | Ash tine. | space. 


1:047 | °710 ‘296 041 47°3 11°8 3°0 37°9 


mS 


+3 


C= 


be 


RESULTS OF TEST. 


‘Weicnr oF “Raat. 
Demy 173" x 224'' = 480 cHowtne 14 lbs. 
- Grammes per pees metres. so 


THICKNESS. Z 
_ Single sheet Was ski 0041 ins. 


_ greenorn. 
Tensile strength on attra 
15 mm. wide (Leunig’s machine) — 
Machine direction =~ 5*51bs. © 
Cross direction — 2°4 lbs. “ 
Mean tensile strength of paper 4°0lbs. — 1°81 Kilos. 


Breakina LENGTH... ... ... 2550 yds. 2324 Metres, 


EIS ae WEIGHT OF SQ. MM, OF 
SECTIONAL AREA... _... . 1161 gms, 


roe OF : STRENGTH DUE TO FoLDING. 3 
On folding 4 timesmean % loss 10°:0% 
On folding 12 times mean % lose 20°0% 


Bursting STRAIN. | 
Libs. per square inch heats 81 lbs. 
Grammes per square centimetre 


ASH, ean 
Seek Percentage of loading ee 42% 


FrBrovs CoMPOSITION. : 
* - Sulphite wood .... 10% 
Mechanical wood 90% 


_ VOLUME’ CoMPOSITION, 


ee Percentage composition 
ee per ¢.c. “by volume. 


Paper | Fibre. Ash | Fibre | Ash | Airspace 
500 ‘479 ‘O21 | 819 0°84 67°3 


By ar Ay sf x 50 


SercrmEN Paper. No. 9. 


Trade Description. 
High-class News. 18 lbs. Demy = 480 sheets. 
Prices on application to Messrs, C. Morgan & Co. 


RESULTS OF TEST. 


WEIGHT OF REAM. 
Demy 174" x 224’ = 480sheets 18 lbs. 


Grammes per square metre ... 67°0 gms, 
THICKNESS, 

Single sheet... act ». 0045 ins. 114 mm. 
STRENGTH 


Tensile strength on strips 
15 mm. wide (Leunig’s machine) 
Machine direction 6°3 lbs. 


Cross direction 4°1 lbs. 

Mean tensile strength of paper 5:2 lbs. 2°36 Kilos. 
BREAKING LENGTH ... sen ... 2578 yds. 2350 Metres. 
BREAKING WEIGHT PER SQ. MM. OF 

SEcTIONAL AREA ... ae 1878 gms. 


Loss or STRENGTH DUE TO FOLDING. 
On folding 4 times mean % loss 154% 
On folding12timesmean%loss 19°2% 


Bourstine STRAIN. 
Lbs. per square inch required 11°4 lbs, 


Grammes per square centimetre 808 gms. 
ASH. 

Percentage of loading ... ph 3°3% 
Fisrovus COMPOSITION. 

Sulphite Wood ... i Res 80% 

Mechanical Wood oe pan 20% 


VOLUME COMPOSITION. 


‘ Grammes per ¢.c Percentage composition 


by volume. 
Paper | Fibre Ash Fibre Ash _ |Air space 
587 568 019 37°9 08 61°3 


SPECIMEN Paper. No. 10. 


Trade Description. 


Bulking Antique Wove Printing. 18 lbs. Demy = 480 sheets. 
Prices on application to Messrs. C. Morgan & Co. 


RESULTS OF TEST. 


Wriant or Ream. 
Demy 174" x 224'’ = 480sheets 18 lbs, 


Grammes per square metre ... 67°0 gms, 
THICKNESS. 

Single sheet ode ao ... °0066 ins. "168 mm, 
STRENGTH. 


Tensile strength on strips 
15mm. wide (Leunig’s machine) 
Machine direction 7°7 lbs. 


Cross direction 4°2 lbs. 

Mean tensile strength of paper _6°0 lbs. 2°72 Kilos. 
BREAKING LENGTH ... tee ... 2975 yds. 2710 Metres. 
BREAKING WEIGHT PER SQ. MM, OF 

SECTIONAL AREA ... ae 1081 gms. 


Loss OF STRENGTH DUE TO FOLDING. 
On folding 4timesmean% loss 35°0% 
Onfolding12timesmean%loss 41°7% 


Bursting STRAIN. 
Lbs. per square inch required 13:1 lbs. 


Grammes per square centimetre 914 gms. 
ASH. 

Percentage of loading ... ie 75% 
Fisrovus CoMPosirTIon. 

Esparto ... seh ies ses 95% 

Sulphite Wood ... ee me 5% 


VOLUME COMPOSITION. 


Grammes per ¢.c. Percentage composition 


by volume. 
Paper Fibre Ash Fibre Ash _ Air space 
“400 °370 030 24°7 12 74:1 


Oy ibe 


ils. 
eee 
IO IN il 


SPECIMEN Paper. No. 11. 


Trade Description. 


Cartridge. 
(Messrs. Lepard & Smiths.) 
Price 23d, per lb. 


RESULTS OF TEST. 
WEIGHT OF REAM. 


Demy 174"’ x 223'/' = 480sheets 29 lbs. 

Grammes per square metre 
THICKNESS. 

Single sheet As ae .. °0055 ins. 
STRENGTH. 

Tensile strength on strips 

15 mm. wide (Leunig’s machine) 

Machine direction 14°5 lbs, 

Cross direction 5°8 lbs. 

Mean tensile strength of paper 10:2 lbs. 
BREAKING LENGTH ... 8139 yds. 
BREAKING WEIGHT PER SQ. MM, OF 

SECTIONAL AREA ... - 
Loss or STRENGTH DUE TO FOLDING. 

On folding 4 times mean % loss 30°4% 

On folding12timesmean%loss 40°2% 
BurRsTING STRAIN. 

Lbs. per square inch required 19°8 lbs, 

Grammes persquare centimetre 
ASH. 

Percentage of loading ... 9:5% 
Fisrous CoMPOSITION. 

Sulphite wood oe Ae 99% 

Mechanical wood ao or 1% 


VOLUME COMPOSITION. 


Grammes per C.C¢. 


Ash 
073 


Fibre 
46°5 


Fibre 
698 


Paper 
‘T71 


Ash 


29 lbs. Demy = 480 sheets. 


107°9 gms, 


"140 mm. 


4°63 Kilos. 
2865 Metres. 


2207 gms 


1391 gms. 


Percentage composition 
by volume. 


Air space 
50°6 


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‘ a 4 


VAN NOSTRAND'S 
“WESTMINSTER” SERIES 


Bound in Uniform Biyles | 
Fully Illustrated. Price $2.00 net each. 


Gas Engines. By W. J.. MARSHALL, Assoc. M.I.Mech.E., 
apd CApT. H. RIALL SANKEY, RE. (Re¢t.).. M.Inst.C.E., 
M.I.Mech.E. 300 Pages, 127 Illustrations. 

List oF ConTENTS : Theory of the Gas Engine:. The Otto Cycle. The 
Two Stroke Cycle. Water Cooling of Gas Engine Parts. Ignition. 
Operating Gas Engines. The Arrangement of a Gas Engine Instal- 
lation. The Testing of Gas Engines. Governing. Gas and Gas 

mProducers.” index. 


Textiles. By A. F. Barxer, M.Sc., with Chapters on the 
Mercerized and Artificial Fibres, and the Dyeing of 
Textile. Materials by W. M. GARDNER, M.Sc., F.CS.; 
Silk Throwing and Spinning, by R. SNow ; the Cotton 
Industry, by W. H. Cook; the Linen Industry, by F 

>: BRADBURY. 370 Pages. . 86 Illustrations. 

ConTEnTS: The History of the Textile Industries ; also of Textile 
Inventions and Inventors. The Wool, Silk, Cotton, Flax, etc., 
Growing Industries. The Mercerized, and Artificial Fibres em- 
ployed in the Textile Industries. The Dyeing of Textile Materials. 
The Principles of Spinning. Processes preparatory to Spinning. 
The Principles of Weaving. The Principles of Designing and 
Colouring. The Principles of Finishing. Textile Calculations. 
The Woollen Industry. The Worsted Industry. The Dress 
Goods, Stuff, and Linings Industry. The Tapestry and Carpet 
Industry. Silk Throwing and Spinning. The Cotton Industry. 
The Linen Industry historically and commercially ; considered. 
Recent Developments and. the Future of the Textile Industries. 
Index. 


Soils and Manures. By J. Aran Murray, B.Sc. 367 
Pages. 33 Illustrations.. - 


ConTENTS: Introductory. The Origin of Soils. Physical Pores 
ties of Soils: Chemistry of Soils. Biology. of Soils. Fertility. 
Principles of: Manuring. Phosphatic’ Manures.. Phosphonitro- 
genous Manures. WNitrogenous. Manures. Potash Manures. 
Compound and Miscellaneous Manures.. General Manures. Farm- 
yard Manure. Valuation of Manures. Composition and Manural 
Value of Various Farm Foods. 


(1) 


THE ““WESTMINSTER? 7 SE Ries 


Gout By James ToncE, M.I.M.E., F.G.S., etc. (Lecturer 


on Mining at Victoria University, Manchester). 283 
Pages. With 46 Illustrations, many of them showing the 
Fossils found in the Coal Measures. 


List oF CONTENTS: History. Occurrence. Mode of Formation 
of Coal Seams. Fossils of the Coal Measures. Botany of the 
Coal-Measure Plants. Coalfields of the British Isles. Foreign 
Coalfields. The Classification of Coals. The Valuation of Coal. 
Foreign Coals and their Values. Uses of Coal. The Production 
of Heat from Coal. Waste of Coal. The Preparation of Coal 
for the Market. Coaling Stations of the World. Index. 


Iron and Steel. By J. H. Sranssre, B.Sc. (Lond.), F.I.C. 
385 Pages. With 86 Illustrations. 


List oF CONTENTS: Introductory. Iron Ores. Combustible and 
other materials used in Iron and Steel Manufacture. Primitive 
Methods of Iron and Steel Production. Pig Iron and its Manu- 
facture. The Refining of Pig Iron in Small Charges. Crucible 
and Weld Steel. The Bessemer Process. The Open Hearth 
Process. Mechanical Treatment of Iron and Steel. Physical 
and Mechanical Properties of Iron and Steel. Iron and Steel 
under the Microscope. Heat Treatment of Iron and Steel. Elec- 
tric Smelting. Special Steels. Index. 


Timber. By J. R. BaterpEN, Assoc.M.Inst.C.E. 334 
Pages. 54 Illustrations. | 


ConTENTS: Timber. The World’s Forest Supply. Quantities of 
Timber used. Timber imports into Great Britain. European 
Timber. Timber of the United States and Canada. Timbers 
of South America, Central America, and West India Islands. Tim- 
bers of India, Burma, and Andaman Islands. Timber of the 
Straits Settlements, Malay Peninsula, Japan and South and 
West Africa. Australian Timbers. Timbers of New Zealand 
and Tasmania. Causes of Decay and Destruction of Timber. 
Seasoning and Impregnation of Timber. Defects in Timber and 
General Notes. Strength and Testing of Timber. ‘“ Figure” in 
Timber. Appendix. Bibliography. 


Natural Sources of Power. By Rosert S. BALL, B.Sc., 
A.M.Inst.C.E. 362 Pages. With 104 Diagrams and 
Illustrations. 


CoNnTENTS: Preface. Units with Metric Equivalents and Abbre- 
viations. Length and Distance. Surface and Area. Volumes. 
Weights or Measures. Pressures. Linear Velocities, Angular 
Velocities. Acceleration. Energy. Power. Introductory 
Water Power and Methods of Measuring. Application of Water 
Power to the Propulsion of Machinery. The Hydraulic Turbine, 


(24) 


THE “ WESTMINSTER” SERIES 


asa, es aS 


Various Types of Turbine. Construction of Water Power Plants. 
Water Power Installations. The Regulation of Turbines. Wind 
Pressure, Velocity, and Methods of Measuring. The Application 
of Wind Power to Industry. The Modern Windmill. Con- 
structional Details. Power of Modern Windmills. Appendices. 
A, B,C. Index. 


Electric Lamps. By Maurice Sotomon, A.C.G.I., 
A.M.I.E.E. 339 Pages. 112 Illustrations. 


ConTENTS: The Principles of Artificial |llumination. The Produc- 
tion of Artificial Illumination. Photometry. Methods of Testing. 
Carbon Filament Lamps. The Nernst Lamp. Metallic Filament 
Lamps. The Electric Arc. The Manufacture and Testing of Arc 
Lamp Carbons. Arc Lamps. Miscellaneous Lamps, Compari- 
son of Lamps of Different Types. 


Liquid and Gaseous Fuels, and the Part they play 


in Modern Power Production. By Professor 
ViviAN B. Lewes, F.IL.C., F.C.S., Prof. of Chemistry, 
Royal Naval College, Greenwich. 350 Pages. With 54 
Illustrations. 


List OF CONTENTS: Lavoisier’s Discovery of the Nature of Com- 
bustion, etc. The Cycle of Animal and Vegetable Life. Method 
of determining Calorific Value. The Discovery of Petroleum 
in America. Oil Lamps, etc. The History of Coal Gas. Calorific 
Value of Coal Gas and its Constituents. The History of Water 
Gas. Incomplete Combustion. Comparison of the Thermal 
Values of our Fuels, etc. Appendix. Bibliography. Index. 


Electric Power and Traction. By F. H. Davies, 
A.M.I.E.E. 299 Pages. With 66 Illustrations. 


List oF CONTENTS: Introduction, The Generation and Distri- 
bution of Power. The Electric Motor. The Application of 
Electric Power. Electric Power in Collieries. Electric Power 
in Engineering Workshops. Electric Power in Textile Factories. 
Electric Power in the Printing Trade. Electric Power at Sea. 
Electric Power on Canals. Electric Traction. The Overhead 
System and Track Work. The Conduit System. The Surface 
Contact System. Car Building and Equipment. Electric Rail- 
ways. Glossary. Index. 


Decorative Glass Processes. By Arruur Louis 
DUTHIE. 279 Pages. 38 Illustrations. 

ConTENTS: Introduction. Various Kinds of Glass in Use: Their 
Characteristics, Comparative Price, etc. Leaded Lights. Stained 
Glass. Embossed Glass. Brilliant Cutting and Bevelling. Sand- 
Blast and Crystalline Giass. Gilding. Silvering and Mosatc. 
Proprietary Processes. Patents. Glossary. 


(3°) 


_FHE “WESTMINSTER” SERIES 


Tae Gas and its Uses for the Production of 


Light, Heat, and Motive Power. By W. H. Y. 
WeBBER, C.F. 282 Pages. “With 71 Illustrations, 


‘List oF ContENTS: The Nature and Properties of Town Gas. The 
History and Manufacture of Town Gas. The Bye-Products of 

’ Coal Gas: Manufacture. Gas Lights’ and Lighting. Practical 
Gas Lighting.. The Cost of Gas Lighting. Heating and Warm- 
ing by Gas. Cooking by Gas. The Healthfulness and Safety 
of Gas in all-its uses. Town Gas for Power Generation} including 
Private Electricity Supply. The Legal Relations of Gas Sup- 
pliers, Consumers, ‘and the Public. Index. 


Electro-Metallurey. By J. B. C. Kersnaw, F.C. 
318 Pages. With 61 Illustrations. ; 


--CONTENTS: Introduction and Historical Survey. Aluminium. 
Production, Details of Processes and Works. Costs. Utiliza- 
- tion: ‘Future of the Metal. Bullion and Gold. Silver Refining 
Process.: Gold Refining Procéssés. Gold Extraction Processes. 
Calcium Carbide and Acetylene Gas. The Carbide Furnace and 
Process. Production. Utilization. Carborundum. Details of 
Manufacture. Properties and Uses. Copper. Copper Refin- 

“ing. Descriptions of Refineries. Costs. Properties and Utiliza- 
tion. .The Elmore and similar Processes. Electrolytic Extrac- 

‘ tion ‘Processes. .Electro-Metallurgical Concentration Processes. 
Ferro-alloys:' Descriptions of Works. Utilization. Glass and 
Quartz Glass! Graphite... Details of Process. Utilization. ‘Iron 
and Steel. Descriptions.of Furnaces and Processes. Yields!and 
Costs. Comparative Costs. Lead. The Salom Process. The Betts 
Refining Process. The Betts Reduction Process. White Lead Pro- 

“cesses. _ Miscellaneous Products. Calcium. Carbon Bisulphide. 
Carbon Tetra-Chloride.. Diamantine. Magnesium, Phosphorus. 
Silicon and its Compounds, Nickel. Wet Processes. Dry 
Processes. Sodium. Descriptions of Cells and Processes. Tin. 
Alkaline Processes for Tin Stripping. Acid Processes for Tin 
Stripping. Salt Processes for Tin Stripping. Zinc. Wet Pro- 
cesses. Dry Processes. Electro-Thermal Processes. Electro- 
Galvanizing. Glossary. Name Index. 


Radio- Tele eRTAP OY. Bye Go E. Monckton, M.LE.E. 
' 389 Pages. ith 173 Diagrams and Illustrations. 


CONTENTS : Preface. Electric Phenomena. Electric Vibrations. 
' Electro-Magnetic Waves. Modified Hertz Waves used in Radio-. 
Telegraphy. Apparatus used for Charging the Oscillator. ; The 
Electric Oscillator : Methods of Arrangement, Practical Details. 
mabe Receiver: Methods of Arrangement, The Detecting Ap- 
*"paratus,,and other-details.. Measurements in ‘Radio-Telegraphy. 
‘The Experimental Station at Elmers End: Lodge-Muirhead 
“System. -Radio- Telegraph Station at Nauen: Telefunken 
System. Station at Lyngby: Poulsen System. The Lodge- 


(4 ) 


THE “WESTMINSTER” SERIES 


Muirhead System, the Marconi System, Telefunken System, and 
Poulsen System. Portable Stations. Radio-Telephony, Ap- 
pendices: The Morse Alphabet. Electrical Units used ih this 
Book. International Control of Radio- -Telegraphy. Index. 


es Rubber and its Manufacture, with Chapters 


on Gutta-Percha and Balata. By H. L. Terry, 
_ F.I.C., Assoc. Inst. M.M: ' 303: ‘Pages. With Illustrations: 


List. or ContTENTS: Preface. Introduction: Historical and 
General. Raw/Rubber. ‘Botanical Origin. Tapping. the Trees. 
Coagulation.. Principal Raw Rubbers of Commerce. Pseudo- 
Rubbers. Congo Rubber, General’’'Considerations. Chemical 
and Physical Properties, Vulcanization. India-rubber Planta- 
‘tions. India-rubber Substitutes. Reclaimed Rubber. Washing 
and Drying of Raw, Rubber, ‘Compounding of Rubber. Rubber 
Solvents and their Recovery. Rubber Solution. Fine Cut. Sheet 
and Articles made therefrom. Elastic Thread. Mechanical 
Rubber Goods. Sundry Rubber Articles. India-rubber Proofed 
Textures. Tyres. India-rubber Boots and Shoes.. Rubber for 
Insulated Wires. Vulcanite Contracts for India-rubber Goods. 
The Testing of Rubber Goods. Gutta-Percha. Balata. Biblio- 
graphy. Index, caer ge (3 


’ 


The Railway eceiictive: What It Is, and Why It is 
What It. Is.. By ‘VAUGHAN. PENDRED, M.Inst.M.E., 
Mem.Inst.M.I. 321 Pages... 94 Illustrations. 


ContTENTS : The Locomotive Engine as a Vehicle—Frames. Bogies. 
The Action of the Bogie. Centre of Gravity. Wheels. Wheel 
‘and Rail. Adhesion. ‘Propulsion. Counter-Balancing. | The Loco- 
motive as a Steam Generator—The Boiler. The Construction of the 
-Boiler.. Stay ~Bolts. The Fire-Box. ‘The Design of Boilers. 

- Combustion. Fuel. ‘The Front End. The. Blast’ ‘Pipe. ‘Steam 
Water. Priming. The Quality of Steam. Superheating. Boiler 
Fittings. The Injector. The Locomotive as a+Steam ’ Engine— 
‘Cylinders and Valves. ‘Friction. Valve Gear. Expansion. The 
Stephenson Link Motion. Walschaert’s: and Joy’s Gears. Slide 
Valves. Compounding, Piston Valves,’ The Indicator. Ten- 
ders, Tank Engines: ‘Lubrication. Brakes. The Running Shed. 
The Work of the Locomotive. eh | 


Glass Manufacture. By Watter RosENHAIN, Superin- 
tendent of ‘the Department of Metallurgy in the National 
Physical Laboratory, late Scientific Adviser in the Glass 
Works of: Messrs. Chance Bros.’ & Co. ise Pages. With 
Illustrations. 


ConTENTS Preface. Definitions. Physical and Chemical Qualities, 
Mechanical, Thermal, and Electrical Properties. Transparency 


5”) 


THE “WESTMINSTER ” .SERIES 


and Colour. Raw materials of manufacture. Crucibles and 
Furnaces for Fusion. Process of Fusion. Processes used in | 
Working of Glass. Bottle. Blown and Pressed. Rolled or 
Plate. Sheet and Crown. Coloured. Optical Glass: Nature 
and Properties, Manufacture. Miscellaneous Products. Ap- 
pendix. Bibliography of Glass Manufacture. Index 


—. 


Precious Stones. By W. Goopcuizp, M.B., B.Ch. 3109 
Pages. With 42 Illustrations. With a Chapter on 
Artificial Stones. By RosBert Dykes. 7 


List oF CONTENTS: Introductory and Historical. Genesis cf 
Precious Stones. Physical Properties. The Cutting and Polish- 
ing of Gems. Imitation Gems and the Artificial Production of 
Precious Stones, The Diamond. Fluor Spar and the Forms of 
Silica. Corundum, including Ruby and Sapphire. Spinel and 
Chrysoberyl. The Carbonates and the Felspars. The Pyroxene 
and Amphibole Groups. Beryl, Cordierite, Lapis Lazuli and the 
Garnets. Olivine, Topaz, Tourmaline and other Silicates. Phos- 
phates, Sulphates, and Carbon Compounds. 


INTRODUCTION TO THE 


Chemistry and Physics of Building Materials. 
By ALAN E. Munsy, M.A. 365 Pages. Illustrated. 


ConTENTS: Elementary Science: Natural Laws and Scientific In- 
vestigations, Measurement and the. Properties of Matter. Air 
and Combustion. Nature and Measurement of Heat and Its 
Effects on Materials. Chemical Signs and Calculations. Water 
and Its Impurities. Sulphur and the Nature of Acids and Bases. 
Coal and Its Products. Outlines of Geology. Building Materials : 
The Constituents of Stones, Clays and Cementing Materials. Clas- 
sification, Examination and Testing of Stones, Brick and Other 
Clays. Kiln Reactions and the Properties of Burnt Clays. Plasters 
and Limes. Cements. Theories upon the Setting of Plasters and 
Hydraulic Materials. Artificial Stone. Oxychloride Cement. 
Asphaite. General Properties of Metals. Iron and Steel. Other 
Metals and Alloys. Timber. Paints: Oils, Thinners and Varnishes; 
Bases, Pigments and Driers. 


Patents, Designs and Trade Marks: The Law 


and Commercial Usage. By KEnnetu R. Swan, 
B.A. (Oxon.), of the Inner Temple, Barrister-at-Law. 
402 Pages. 


ConTENTS: Table of Cases Cited—Part I.—Letters Patent. Intro- 
duction. General. Historical. I., II., III. Invention, Novelty, 


(6 ) 


THE “WESTMINSTER ”: SERIES 


Subject Matter, and Utility the Essentials of Patentable Invention. 
IV. Specification. V. Construction of Specification. VI. Who 
May Apply for a Patent. VII. Application and Grant. VIII. 
Opposition. IX. Patent Rights. Legal Value. Commercial 
Value.’ X. Amendment. XI. Infringement of Patent. XII. 
Action for Infringement. XIII. Action to Restrain Threats. 
XIV. Negotiation of Patents by Sale and Licence. XV. Limita- 
tions on Patent Right. XVI. Revocation. XVII. Prolonga- 
tion. XVIII. Miscellaneous. XIX. Foreign Patents... XX. 
Foreign Patent Laws: United States of America. Germany. 
France. Table of Cost, etc., of Foreign Patents. APPENDIx A.— 
1. Table of Forms and Fees. 2. Cost of Obtaining a British 
Patent. 3. Convention Countries. Part II.—Copyright in 
Design. Introduction. I. Registrable Designs. II. Registra- 
tion. III. Marking. IV. Infringement. APPENDIx B.—1. 
Table of Forms and Fees. 2. Classification of Goods. Part 
III.—Tvrade Marks. Introduction. I. Meaning of Trade Mark. 
II. Qualification for Registration. III. Restrictions on Regis- 
tration. IV. Registration. V. Effect of Registration. VI. 
Miscellaneous. APPENDIx C.—Table of Forms and Fees, INDICEs. 
1. Patents. 2. Designs. 3. Trade Marks. 


The Book: Its History and Development. By 
Cyrit Davenport, V.D., F.S.A. 266 Pages. With 
7 Plates and 126 Figures in the text. 


List oF CONTENTS: Early Records. Rolls, Books and Book 
bindings. Paper. Printing. Illustrations. Miscellanea. 
Leathers. The Ornamentation of Leather Bookbindings without 
Gold. The Ornamentation of Leather Bookbindings with Gold. 
Bibliography. Index. 


The Manufacture of Paper. By R.W.SinpAtt, F.CS., 
Consulting Chemist to the Wood Pulp and Paper Trades ; 
Lecturer on Paper-making for the Hertfordshire County 
Council, the Bucks County Council, the Printing and 
Stationery Trades at Exeter Hall (1903-4), the Institute 
of Printers; Technical Adviser to the Government of 
India, 1905. 275 Pages. 58 Illustrations. 

ConTENTS: Preface. List of Illustrations. Historical Notice. Cel- 
lulose and Paper-making Fibres. The Manufacture of Paper from 
Rags, Esparto and Straw. Wood Pulp and Wood Pulp Papers. 
Brown Papers and Boards. Special kinds of Paper. Chemicals 
used in Paper-making. The Process of “ Beating.”” The Dye- 
ing and Colouring of Paper Pulp. Paper Mill Machinery. The 
Deterioration of Paper. Bibliography. Index. 


() 


THE ‘““WESTMINSTER” SERIES 


Wood Pulp and its Applications. By C. F. Cross, 
B.Sc., F.LC.,-E. J. BEVAN,-F.I.C.,-'and R:. W. SINDALL, 
F.C.S. 266 pages. 36 Illustrations. 


ContTENTs: The Structural Elements of Wood. Cellulose as a 
Chemical. Sources of Supply. Mechanical Wood Pulp. Chemical 
Wood Pulp. The Bleaching of Wood Pulp. News and Printings. 
Wood Pulp Boards. Utilisation of Wood Waste. Testing of 
Wood Pulp for Moisture. Wood Pulp and the Textile Industries, 
Bibliography. Index. © | 


Photography: its Principles and Applications. 
By ALFRED WATKINS, F.R.P.S. 342 pages. 98 Illus- 
trations. 


‘- ConrTENTS: First Principles. Lenses. Exposure Influences. ‘Prac- 
tical Exposure: Development Influences. Practical Develop- 
ment. Cameras and Dark Room. Orthochromatic Photography. 
Printing Processes. Hand Camera Work. Enlarging and Slide 
Making. Colour Photography. General Applications. Record 
Applications, Science Applications. Plate Speed Testing. Pro- 
cess Work. Addenda. Index. 


IN PREPARATION. 


Commercial Paints and Painting. By A. S. Jenn- 
~ InGS, Hon. Consulting Examiner, City, and Guilds of 
_ London Institute. | i 


Brewing and Distilling. By James Grant, F.S.C. 


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